ES2909715T3 - Electrode Array Preparation Method - Google Patents

Abstract

A method of preparing an electrode array, comprising the steps of: 1) pre-drying a vacuum separator at a pressure of less than 25 kPa and a temperature of 50°C to 150°C in a drying chamber to obtain a pre-dried separator; 2) stacking at least one anode, at least one cathode and at least one pre-dried separator interposed between the at least one anode and at least one cathode to obtain the set of electrodes; 3) drying the electrode assembly under vacuum at a temperature of about 70°C to about 150°C; 4) fill the drying chamber with dry air or inert gas; and 5) repeating steps 3) and 4) at least 5 times; where each iteration of step 3) lasts a period of time from 5 minutes to 12 hours; wherein the water content of the predried trap is less than 80 wppm, based on the total weight of the predried trap, as measured by coulometric Karl-Fischer titration.

Description

DESCRIPTION

Electrode Array Preparation Method

field of invention

The present invention relates to lithium ion batteries in the area of sustainable energy application. More particularly, this invention relates to methods of preparing electrode assemblies.

Background of the invention

Lithium ion batteries (LIBs) have attracted considerable interest in the last two decades for a wide range of applications in portable electronic devices such as cell phones and laptop computers. Due to the rapid development of the electric vehicle (EV) market and grid energy storage, high-performance, low-cost BILs currently offer one of the most promising options for large-scale energy storage devices.

Currently, electrodes are prepared by dispersing fine powders of a battery electrode active material, a conductive agent, and a binding material in an appropriate solvent. The dispersion can be coated on a current collector, such as copper or aluminum foil, and then dried at an elevated temperature to remove the solvent. The cathode and anode sheets are then stacked or rolled with the separator separating the cathode and anode to form a battery. The separator is a physical barrier interposed between the anode and the cathode, which prevents physical contact between them.

The manufacturing process for a lithium ion battery is sensitive to moisture. A battery with a high water content leads to significant attenuation of electrochemical performance and affects battery stability. Moisture in a battery can originate from various sources. A possible source of moisture is from the separator. The separator can absorb moisture during manufacturing, storage, and transportation. This is particularly the case when the separator is placed and stored in a humid environment. To address the sensitive issue of electrode array moisture, it is important to dry the separator before forming an electrode array to reduce the water content in the battery.

Korean Patent No. 101497348 B1 describes a method for preparing an electrode assembly. The method comprises the steps of forming a laminate by stacking a cathode, an anode and a spacer interposed between the two electrodes; heat the laminate; and pressurizing the heated laminate. The heating process melts part of the separator fibers so that the electrodes and separator can be combined. However, this method does not dry the separator before it is assembled.

Korean Patent No. 101495761 B1 describes a method for preparing an electrode assembly. The method comprises the steps of preparing the negative and positive electrode plates; arranging a positive electrode plate, a negative electrode plate and a spacer to form an electrode assembly; forming a roll by winding the electrode assembly; dry the roll However, this method also does not dry the spacer before it is assembled.

Korean Patent No. 100759543 B1 describes a method for preparing an electrode assembly of a lithium ion polymer battery. The method comprises the steps of preparing a positive electrode plate and a negative electrode plate; prepare a separator; heat the separator; and interposing the heated separator between the two electrode plates, wherein the separator is heated at a high temperature for 1-3 minutes. However, the heating process is used to remove residual stress within the separator to prevent separator shrinkage due to battery overheating.

The absence of a pre-drying process for the separators in the existing method introduces water into the electrode assemblies, which can affect cycle stability and LIB current intensity. In view of the foregoing, there remains a need to develop a method of drying LIB separators to a low water content prior to assembling them into an electrode assembly.

Summary of the invention

The aforementioned needs are met by various aspects and embodiments disclosed herein.

In one aspect, there is provided herein a method of preparing an electrode assembly, comprising the steps of:

1) pre-drying a separator under vacuum at a temperature of from about 50°C to about 150°C in a drying chamber to obtain a pre-dried separator;

2) stacking at least one anode, at least one cathode, and at least one pre-dried spacer interposed between the at least one anode and at least one cathode to obtain the set of electrodes; Y

3) Dry the electrode array.

In some embodiments, the spacer is a nonwoven fabric consisting of natural or polymeric fibers, and wherein the polymeric fibers have a melting point of 200°C or higher.

In certain embodiments, the spacer is made from a nonwoven fabric of polymeric fibers selected from the group consisting of polyolefin, polyethylene, high-density polyethylene, linear low-density polyethylene, low-density polyethylene, ultra-high molecular weight polyethylene, polypropylene, polypropylene/polyethylene copolymer, polybutylene, polypentene, polyacetal, polyamide, polycarbonate, polyimide, polyether ether ketone, polysulfones, polyphenylene oxide, polyphenylene sulfide, polyacrylonitrile, polyvinylidene fluoride, polyoxymethylene, polyvinylpyrrolidone, polyester, polyethylene terephthalate, polyethylene terephthalate polybutylene, polyethylene naphthalene, polybutylene naphthalate, and combinations thereof.

In some embodiments, the separator is pre-dried for a period of time from about 2 hours to about 12 hours, or from about 2 hours to about 8 hours.

In certain embodiments, the separator is pre-dried at a pressure of less than 25 kPa, less than 15 kPa, less than 10 kPa, or less than 5 kPa.

In some embodiments, the drying chamber is filled with dry air or inert gas after step 1).

In certain embodiments, step 1) and the gas filling step are repeated at least 2 times.

In some embodiments, the spacer comprises a porous base material and a protective porous layer coated on one or both surfaces of the porous base material, wherein the protective porous layer comprises a binder material and an inorganic filler, and wherein the peel strength between the porous base material and the protective porous layer is 0.04 N/cm or more, or 0.1 N/cm or more.

In certain embodiments, the inorganic filler is selected from the group consisting of AhO3, SiO2, TiO2, ZrO2, BaOx, ZnO, CaCO3, TiN, AlN, MTO3, K2OnTiO2, Na2OmTiO2, and combinations thereof, where X is 1 or two; M is Ba, Sr or Ca; n is 1, 2, 4, 6 or 8; and m is 3 or 6.

In some embodiments, the binder material is selected from the group consisting of styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile copolymer, acrylonitrile-butadiene rubber, nitrile-butadiene rubber, acrylonitrile-styrene-butadiene copolymer, rubber. acrylic, butyl rubber, fluorine rubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene/propylene copolymers, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene , latex, acrylic resins, phenolic resins, epoxy resins, carboxymethylcellulose, hydroxypropylcellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylcellulose, cyanoethylsucrose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyac rylate, polymethacrylic acid, polymethacrylate, polyacrylamide, polyurethane, fluoropolymer, chlorinated polymer, alginic acid salt, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropene, and combinations thereof.

In certain embodiments, the weight ratio of inorganic filler to binder material is from about 99:1 to about 1:1.

In some embodiments, the spacer is from about 1 µm to about 80 µm thick.

In certain embodiments, the separator has a porosity of from about 40% to about 97%.

In some embodiments, the electrode array is dried at a pressure of less than 25 kPa, less than 15 kPa, less than 10 kPa, or less than 5 kPa.

In certain embodiments, the electrode assembly is dried for a period of time from about 2 hours to about 24 hours, or from about 4 hours to about 12 hours.

In some embodiments, the electrode array is dried at a temperature of from about 70°C to about 150°C.

In certain embodiments, the water content of the separator is greater than 500 ppmw, based on the weight entire separator.

In some embodiments, the water content of the pre-dried separator is less than 50 ppm by weight, based on the total weight of the pre-dried separator.

In certain embodiments, the water content of the dry electrode assembly is less than 20 ppm by weight, based on the total weight of the dry electrode assembly.

In another aspect, a lithium battery comprising the electrode assembly prepared by the method disclosed herein is provided herein.

Brief description of the drawings

Figure 1 represents the cycle performance of an electrochemical cell containing an electrode array prepared by the method described in Example 2.

Figure 2 represents the cycle performance of an electrochemical cell containing an electrode array prepared by the method described in Example 4.

Figure 3 represents the cycling performance of an electrochemical cell containing an electrode array prepared by the method described in Example 6.

Detailed description of the invention

A method of preparing an electrode assembly is provided herein, comprising the steps of:

1) pre-drying a separator under vacuum at a temperature of from about 50°C to about 150°C in a drying chamber to obtain a pre-dried separator;

2) stacking at least one anode, at least one cathode, and at least one pre-dried spacer interposed between the at least one anode and at least one cathode to obtain the set of electrodes; Y

3) Dry the electrode array.

The term "electrode" refers to a "cathode" or an "anode".

The term "positive electrode" is used interchangeably with cathode. Likewise, the term "negative electrode" is used interchangeably with anode.

The term "binding material" refers to a chemical or substance that can be used to hold the battery's active electrode material and conductive agent in place, or a chemical or substance that is used to bind an inorganic charge. to a porous base material and to each other.

The term "water-based binder material" refers to a water-soluble or water-dispersible binder polymer. Some non-limiting examples of the water-based binder material include styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acryl rubber, butyl rubber, fluorine rubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene copolymers /propylene, polybutadiene, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, ethylene/propylene/diene copolymers, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resins, acrylic resins, phenolic resins, epoxy resins, polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, and combinations thereof.

The term "organic-based binder material" refers to a binder dissolved or dispersed in an organic solvent, in particular, N-methyl-2-pyrrolidone (NMP). Some non-limiting examples of the organic-based binder material include polytetrafluoroethylene (PTFE), perfluoroalkoxy polymer (PFA), polyvinylidene fluoride (PVDF), tetrafluoroethylene (TFE) and hexafluoropropylene (HFP) copolymer, fluorinated ethylene-propylene copolymer (FEP ), terpolymer of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride, and combinations thereof.

The term "conductive agent" refers to a chemical or substance that enhances the electrically conductive property of an electrode.

The term "apply" as used herein refers to an act of placing or spreading a substance onto a surface.

The term "squeegee coating" refers to a process for making large-area films on rigid or flexible substrates. The thickness of the coating can be controlled by an adjustable gap width between a coating paddle and a coating surface, which allows the deposition of variable wet film thicknesses.

The term "current collector" refers to a support for coating the active material of the battery electrode and a chemically inactive high concentration electron conductor to maintain an electrical current flowing to the electrodes during the charging or discharging of a secondary battery. .

The term "pre-drying" refers to an act of removing solvent or water from a material.

The term "water content" is used interchangeably with moisture content.

The term "electrode array" refers to a structure comprising at least one positive electrode, at least one negative electrode, and at least one spacer interposed between the positive electrode and the negative electrode.

The term "room temperature" refers to interior temperatures from about 18°C to about 30°C, for example, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30 °C In some embodiments, room temperature refers to a temperature of about 20°C /-1°C or /-2°C or /-3°C. In other embodiments, room temperature refers to a temperature of about 22°C or about 25°C.

The expression "atmospheric pressure" refers to the pressure exerted by the weight of the atmosphere, which has an average value of 101,325 Pa at sea level.

The term "C-rate" refers to the charge or discharge rate of a cell or battery, expressed in terms of its total storage capacity in Ah or mAh. For example, a rate of 1 C means the use of all the stored energy in one hour; 0.1 C means 10% power utilization in one hour and full power in 10 hours; and 5 C means full energy utilization in 12 minutes.

The expression "ampere-hours (Ah)" refers to a unit used to specify the storage capacity of a battery. For example, a battery with a capacity of 1 Ah can supply a current of one amp for one hour or 0.5 A for two hours, etc. Therefore, 1 ampere-hour (Ah) is the equivalent of 3,600 coulombs of electrical charge. Similarly, the term "milliamp-hour (mAh)" also refers to a unit of a battery's storage capacity and is 1/1,000th of an amp-hour.

The term "battery cyclic life" refers to the number of complete charge/discharge cycles a battery can complete before its rated capacity drops below 80% of its initial rated capacity.

In the following description, all numbers disclosed herein are approximate values, regardless of whether the word "about" or "approximate" is used in connection therewith. They can vary by 1 percent, 2 percent, 5 percent, or sometimes 10 to 20 percent. Whenever a numerical range with a lower limit, RL, and an upper limit, Ru, is disclosed, any number that falls within the range is specifically disclosed. In particular, the following numbers within the range are specifically disclosed: R=RLk*(RU-RL), where k is a variable ranging from 1 percent to 100 percent with a 1 percent increase, that is, k is 1 percent, 2 percent, 3 percent, 4 percent, 5 percent,..., 50 percent, 51 percent, 52 percent,..., 95 percent, 96 percent, 97 percent, 98 percent, 99 percent, or 100 percent. Still further, any numerical range defined by two R numbers as defined above is also specifically disclosed.

Polymers such as nylon, polyamide, polyester, and polyvinyl alcohol are known to be hygroscopic and absorb moisture during manufacture or during storage in an air atmosphere. These polymers will re-absorb moisture during transport. However, humidity control during transport is complex and expensive. Therefore, spacers made from these materials must be dried before further processing. In general, the separators are dried after they are assembled into an electrode assembly. However, it has been difficult to thoroughly dry all the materials, including the cathode, anode, and separator, simultaneously to a low moisture content after assembly. This is especially true when the separators have been stored in humid conditions prior to assembly.

In each of stages 1 and 3, a vacuum is made. The reason why drying is carried out in these two stages is that a large amount of moisture adhering to the separator cannot be removed satisfactorily by drying only in stage 3. Residual moisture in the separator causes, for example, a problem. such that residual moisture on the electrodes and in an electrolyte solution results in decomposition of the electrolyte solution, or such a problem that the quality of the active materials of the electrode is impaired. Therefore, moisture removal is crucial.

The separator may comprise woven or nonwoven polymeric fibers, natural fibers, carbon fibers, glass or ceramic fibers. In certain embodiments, the spacer comprises woven or nonwoven polymeric fibers.

In some embodiments, the fibers of the nonwoven or woven are made from organic polymers, such as polyolefin, polyethylene (PE), high density polyethylene, linear low density polyethylene, low density polyethylene, ultrahigh molecular weight polyethylene, polypropylene ( PP), polypropylene/polyethylene copolymer, polybutylene, polypentene, polyacetal, polyamide, polycarbonate, polyimide (PI), polyether ether ketone, polysulfones, polyphenylene oxide, polyphenylene sulfide, polyacrylonitrile, polyvinylidene fluoride, polyoxymethylene, polyvinylpyrrolidone, polyester, polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalene, polybutylene naphthalate, derivatives thereof, or a combination thereof. In certain embodiments, the spacer is made from polyolefin fibers selected from the group consisting of polyethylene, high-density polyethylene, linear low-density polyethylene, low-density polyethylene, ultra-high molecular weight polyethylene, polypropylene, polypropylene/polyethylene copolymer, and combinations of them. In some embodiments, the spacer is made from polymeric fibers selected from the group consisting of polyester, polyacetal, polyamide, polycarbonate, polyimide, polyether ether ketone, polyethersulfone, polyphenylene oxide, polyphenylene sulfide, polyethylene naphthalene, and combinations thereof. . In other embodiments, the polymeric fiber is not polyethylene, high density polyethylene, linear low density polyethylene, low density polyethylene, ultrahigh molecular weight polyethylene, polypropylene, or polypropylene/polyethylene copolymer. In further embodiments, the polymeric fiber is not polyacetal, polyethersulfone, polyphenylene oxide, polyphenylene sulfide, or polycarbonate. In still other embodiments, the polymeric fiber is not polyamide, polyimide, or polyether ether ketone. But all other known polymeric fibers or many natural fibers can also be used.

In certain embodiments, the spacer disclosed herein has a melting point of 100°C or higher, 110°C or higher, 120°C or higher, 130°C or higher, 140°C or higher, 150°C or higher, 160 °C or higher, 170 °C or higher, 180 °C or higher, 190 °C or higher, 200 °C or higher, 210 °C or higher, 220 °C or higher, 230 °C or higher , 240 °C or higher or 250 °C or higher. In some embodiments, the spacer has a melting point of from about 100°C to about 300°C, from about 120°C to about 300°C, from about 100°C to about 250°C, from about 120°C to about 250°C, about 140°C to about 250°C, about 160°C to about 250°C, about 180°C to about 250°C, or about 200°C to about 250°C.

In some embodiments, the water content of the separator is from about 100 ppm to about 5,000 ppm, from about 100 ppm to about 2,500 ppm, from about 100 ppm to about 1,000 ppm, from about 500 ppm to about 5,000 ppm, from about 500 ppm to about 5,000 ppm. ppm to about 4,000 ppm, from about 500 ppm to about 3,000 ppm, from about 500 ppm to about 2,000 ppm, or from about 500 ppm to about 1,000 ppm by weight, based on the total weight of the separator. In certain embodiments, the water content of the separator is greater than about 100 ppm, greater than about 500 ppm, greater than about 1,000 ppm, greater than about 1,500 ppm, greater than about 2,000 ppm, greater than about 3,000 ppm, or greater than about 4,000 ppm by weight, based on the total weight of the separator.

To improve the thermal stability of the separator, fibers having a melting temperature of 200°C or higher should be used. In some embodiments, the fibers are selected from polyester. Some non-limiting examples of suitable polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalene, polybutylene naphthalate, derivatives thereof, and combinations thereof. The separator having a high melting point shows high thermal stability and therefore can be pre-dried at a high temperature without thermal shrinkage. In addition, high melting point separators allow higher pre-drying temperatures, which increases the rate of water evaporation and increases pre-drying efficiency.

The nonwoven fabric can be produced by a publicly known process. Some non-limiting examples of suitable processes include dry process, spunbond process, water needle process, water jet bonding process, wet process, melt blown process, and the like.

The spacer may be in uncoated or coated form. In some embodiments, the spacer is uncoated and does not comprise a protective porous layer. In certain embodiments, the spacer is coated and comprises a porous base material and a protective porous layer coated on one or both surfaces of the porous base material, wherein the protective porous layer comprises a binder material and an inorganic filler. In certain embodiments, the inorganic filler is selected from the group consisting of AhO3, SiO2, TO2, ZrO2, BaOx, ZnO, CaCO3, TiN, AIN, and combinations thereof, where x is 1, or 2.

In certain embodiments, the inorganic filler has an average diameter of from about 100 nm to about 2,000 nm, from about 100 nm to about 1,000 nm, from about 250 nm to about 1,500 nm, from about 300 nm to about 3 pm, from about 500 nm. nm to about 4.5 pm, from about 500 nm to about 6 pm, from about 1 |jm to about 20 |jm, from about 10 jim to about 20 |jm, from about 1 |jm to about 15 jim, from about 1 jim to about 7.5 jim, from about 1 jim to about 4.5 jim , from about 1 jim to about 3 jim, or from about 800 nm to about 2.5 jim.

An advantage of the coated spacer is that it has exceptional safety and shows little or no high temperature shrinkage. This is because the inorganic filler adhering to the porous base material has a melting point that is well above the safety-relevant temperature range of electrochemical cells and thus suppresses thermal shrinkage of the separator.

In some embodiments, the thickness of a coated or uncoated spacer is from about 10 μm to about 200 μm, from about 30 μm to about 100 μm, from about 10 μm to about 75 μm, from about 10 μm to about 50 μm, from about 10 jim to about 20 jim, from about 15 jim to about 40 jim, from about 15 jim to about 35 jim, from about 20 jim to about 40 jim, from about 20 jim to about 35 jim, from about 20 jim to about 30 jim, from about 30 jim to about 60 jim, from about 30 jim to about 50 jim, or from about 30 jim to about 40 jm.

In certain embodiments, the thickness of a coated or uncoated spacer is less than 100 jim, less than 80 jim, less than 60 jim, less than 40 jim, less than 35 jim, less than 30 jim, less than 25 jim, or less to 20 Jim. The thinnest separators allow to build very compact batteries with a high energy density. Also, if the separator is thin enough, moisture can evaporate at high drying rates.

In some embodiments, the coated or uncoated separator has a porosity of from about 50% to about 97%, from about 50% to about 95%, from about 50% to about 80%, from about 55%. % to about 90%, from about 55% to about 80%, from about 60% to about 95%, from about 60% to about 90%, from about 60% to about 80% , from about 65% to about 90%, from about 65% to about 80%, from about 70% to about 90%, from about 70% to about 80%, from about 75% to about 90% or from about 80% to about 90%.

The nature of the separator disclosed herein comprises a particularly useful combination of thickness and porosity, meeting the requirements for separators in high power batteries, especially high power lithium batteries.

In some embodiments, the coated or uncoated spacer may be dried in a vacuum drying chamber prior to assembly. In certain embodiments, the drying chamber is connected to a vacuum pump so that the pressure in the chamber can be reduced. The pressure is reduced enough to lower the boiling point of water. Therefore, the drying time can be reduced considerably. In some embodiments, the drying chamber is connected to a central vacuum supply, thereby allowing multiple vacuum drying ovens to operate simultaneously. In some embodiments, the number of vacuum drying ovens connected to a central vacuum supply varies from 1 to 20, depending on the number of pumps in operation.

Low drying temperature cannot efficiently remove water from the separator, while high drying temperature can cause cracking and embrittlement of the porous protective layer and melting of the porous base material. In certain embodiments, the coated or uncoated spacer can be vacuum dried at a temperature of from about 50°C to about 150°C, from about 60°C to about 150°C, from about 70°C to about 150°C. , from about 80 °C to about 150 °C, from about 90 °C to about 150 °C, from about 100 °C to about 150 °C, from about 100 °C to about 140 °C, from about 100 °C at about 130°C, from about 100°C to about 120°C, from about 100°C to about 110°C, or from about 110°C to about 130°C. In certain embodiments, the coated or uncoated spacer can be vacuum dried at a temperature of from about 80°C to about 150°C. In some embodiments, the coated or uncoated spacer may be vacuum dried at a temperature of about 80°C or higher, about 90°C or higher, about 100°C or higher, about 105°C or higher, about 110°C. C or higher, about 115 °C or higher, about 120 °C or higher, about 125 °C or higher, about 130 °C or higher, about 135 °C or higher, about 140 °C or higher, about 145 °C or higher or about 150 °C or higher. In certain embodiments, the coated or uncoated spacer may be vacuum dried at a temperature of less than 150°C, less than 145°C, less than 140°C, less than 135°C, less than 130°C, less than 125°C, below 120°C, below 115°C, below 110°C, below 105°C, below 100°C or below 90°C.

The conventionally used separators made of polypropylene fibers and the separators made of Cellulose pulps are less resistant to heat compared to other materials. When the separator is dried at a temperature of 100°C or higher, significant deterioration of the separators occurs, such as melting and charring. For lined spacers composed of heat resistant materials as the porous base material, when the spacer dries at temperatures above 150°C, significant deterioration of the binder material in the protective porous layer occurs. In particular, when the binder material is a water-based binder material, such as carboxymethylcellulose (CMC), which is considered a brittle binder. In this case, the aqueous binder is likely to become brittle, resulting in a brittle protective porous layer, which can break after a small deformation. Damage to a separator can have a serious adverse effect on the performance and safety of a secondary lithium-ion battery.

In some embodiments, the period of time to dry the coated or uncoated separator under vacuum is from about 15 minutes to about 24 hours, from about 15 minutes to about 20 hours, from about 15 minutes to about 12 hours, from about 15 minutes hours to about 8 hours, from about 1 hour to about 24 hours, from about 1 hour to about 20 hours, from about 1 hour to about 12 hours, from about 2 hours to about 20 hours, from about 2 hours to about 16 hours hours, from about 2 hours to about 8 hours, from about 2 hours to about 6 hours, or from about 2 hours to about 4 hours. In some embodiments, the period of time to dry the coated or uncoated separator under vacuum is from about 2 hours to about 24 hours or from about 4 hours to about 16 hours. In certain embodiments, the period of time to dry the coated or uncoated separator under vacuum is at least 15 minutes, at least 30 minutes, at least 1 hour, at least 1.5 hours, at least 2 hours, at least 3 hours. , at least 4 hours, at least 5 hours or at least 10 hours. In some embodiments, the period of time to dry the coated or uncoated separator under vacuum is less than 24 hours, less than 10 hours, less than 5 hours, less than 4 hours, less than 3 hours, less than 2 hours, less to 1.5 hours, less than 1 hour or less than 30 minutes.

In certain embodiments, the pre-drying step comprises drying the coated spacer with two stages of drying, the first stage and the second stage, wherein the temperature of the first stage is lower than that of the second stage. A lower temperature in the first stage prevents rapid surface moisture loss and increases product quality by virtually eliminating drying non-uniformity. If the drying is too fast or the temperature is too high, this can cause uneven drying and can cause the protective porous layer to shrink unevenly, thus causing a reduction in the peel strength of the separator.

The temperature in the first phase may be within the range of 50°C to 90°C. A partially dry separator is obtained from the first phase. In some embodiments, the separator may be vacuum dried in the first stage at a temperature of about 50°C or higher, about 60°C or higher, about 70°C or higher, or about 80°C or higher. In certain embodiments, the separator may be vacuum dried in the first stage at a temperature of less than 90°C, less than 85°C, less than 80°C, less than 75°C, or less than 70°C.

A lower temperature in the first phase is beneficial in retarding drying to prevent cracking or embrittlement of the protective porous layer. The surface of the protective porous layer should be dried slowly to reduce the possibility of surface cracking, since the interior of the protective porous layer dries more slowly than the surface of the protective porous layer.

Drying time for the first phase can range from about 5 minutes to about 4 hours, from about 5 minutes to about 2 hours, or from about 15 minutes to about 30 minutes. In some embodiments, the drying time for the first phase is at least 5 minutes, at least 15 minutes, at least 30 minutes, at least 1 hour, at least 1.5 hours, at least 2 hours, or at least 3 hours. In certain embodiments, the drying time for the first phase is less than 4 hours, less than 3 hours, less than 2 hours, less than 1.5 hours, less than 1 hour, less than 30 minutes, or less than 15 minutes. .

The temperature in the second phase can be within the range of from about 80°C to about 150°C, from about 100°C to about 150°C, or from about 100°C to about 140°C. In some embodiments, the separator may be vacuum dried in the second stage at a temperature of about 80°C or higher, about 90°C or higher, about 100°C or higher, about 110°C or higher, about 120°C or higher, about 130 °C or higher, or about 140 °C or higher. In certain embodiments, the separator may be vacuum dried in the second stage at a temperature of less than 150°C, less than 140°C, less than 130°C, less than 120°C, or less than 110°C.

The second phase drying time can range from about 15 minutes to about 4 hours, from about 5 minutes to about 2 hours, or from about 15 minutes to about 30 minutes. In some embodiments, the drying time for the second phase is at least 5 minutes, at least 15 minutes, at least 30 minutes, at least 1 hour, at least 1.5 hours, at least 2 hours. or at least 3 hours. In certain embodiments, the drying time for the second phase is less than 4 hours, less than 3 hours, less than 2 hours, less than 1.5 hours, less than 1 hour, less than 30 minutes, or less than 15 minutes. .

Any vacuum pump that can reduce the pressure of the drying chamber can be used herein. Some non-limiting examples of vacuum pumps include dry vacuum pumps, turbo pumps, rotary vane vacuum pumps, cryogenic pumps, and sorption pumps.

In some embodiments, the vacuum pump is an oil-free pump. The oil-free pump works without the need for oil in the parts of the pump that are exposed to the gases being pumped or to partial vacuum. Thus, any gas flowing countercurrent through the pump is free of oil vapour. Creeping oil vapor deposited on separator surfaces can reduce the electrochemical performance of a battery. An example of this type of pump is a diaphragm vacuum pump.

In some embodiments, the separator is pre-dried at atmospheric pressure. In certain embodiments, the pre-drying step is performed in a vacuum state. In further embodiments, the vacuum state is maintained at a pressure within the range from about 1x10-4 Pa to about 1x104 Pa, from about 1x10-4Pa to about 7.5x103 Pa, from about 1x10-4Pa to about 5x103 Pa, from about 1x10-4Pa to about 5x103 Pa. about 1x10-4Pa to about 4x103 Pa, from about 1x10-4Pa to about 3x103 Pa, from about 1x10-4Pa to about 2x103 Pa, from about 1x10-4Pa to about 1x103 Pa, from about 1x103 Pa to about 5x104 Pa, from about 1x103 Pa to approx. 1x104 Pa, from approx. 1x103 Pa to approx. 7.5x103 Pa, from approx. 1x103 Pa to approx. 5x103 Pa, from approx. 1x103 Pa to approx. approximately 2x103 Pa. In certain embodiments, the vacuum state is maintained at a pressure less than approximately 1x104 Pa, i less than about 7.5 x 103 Pa, less than about 5 x 103 Pa, less than about 4 x 103 Pa, less than about 3 x 103 Pa, less than about 2 x 103 Pa, or less than about 1 x 103 Pa. In some embodiments, the vacuum state is maintained at about 1x104 Pa, about 7.5x103 Pa, about 5x103 Pa, about 4x103 Pa, about 3x103 Pa, about 2x103 Pa or about 1x103 Pa.

To reduce the power required for the pumps, a condenser can be provided between the drying chamber and the pump when the separator is being dried. The condenser condenses the water vapor, which is then separated.

In some embodiments, after a predetermined drying time period, the drying chamber is vented directly to a gas reservoir containing dry air or inert gas through a gas inlet valve. Filling the drying chamber with dry air or inert gas can remove the water vapor in the drying chamber, thereby increasing the water removal efficiency of the electrode assembly. In certain embodiments, the gas reservoir is a cylinder of nitrogen gas. In some embodiments, the inert gas is selected from the group consisting of helium, argon, neon, krypton, xenon, nitrogen, carbon dioxide, and combinations thereof. In certain embodiments, the water content of the dry air or inert gas is maintained less than or equal to 10 ppm, less than or equal to 8 ppm, less than or equal to 5 ppm, less than or equal to 4 ppm, less than or equal to 3 ppm, less than or equal to 2 ppm or less than or equal to 1 ppm.

In some embodiments, the dry air or inert gas is preheated before entering the drying chamber. In certain embodiments, the temperature of the dry air or inert gas is from about 70°C to about 130°C, from about 70°C to about 110°C, from about 70°C to about 100°C, from about 70°C C to about 90°C, from about 70°C to about 80°C, from about 80°C to about 155°C, from about 80°C to about 120°C, from about 80°C to about 100°C , from about 90 °C to about 155 °C, from about 90 °C to about 130 °C, from about 90 °C to about 100 °C, from about 70 °C to about 155 °C, from about 100 °C at about 130°C or from about 100°C to about 120°C. In some embodiments, the dry air or inert gas is preheated to a temperature of from about 70°C to about 155°C before entering the drying chamber. In certain embodiments, the dry air or inert gas is preheated to at least 70°C, at least 80°C, at least 90°C, at least 100°C, at least 110°C, or at least 120°C.

In certain embodiments, the dry air or inert gas remains in the drying chamber for a period of time from about 30 seconds to about 2 hours, from about 1 minute to about 1 hour, from about 5 minutes to about 30 minutes, about 5 minutes to about 15 minutes, about 5 minutes to about 10 minutes, about 10 minutes to about 30 minutes, about 10 minutes to about 20 minutes, about 10 minutes to about 15 minutes, about 15 minutes to about 1 hour, from about 15 minutes to about 30 minutes, from about 15 minutes to about 20 minutes, or from about 30 minutes to about 1 hour. In some embodiments, the dry air or inert gas remains in the drying chamber for a period of time from about 30 seconds to about 2 hours, from about 5 minutes to about 2 hours. hours or from about 15 minutes to about 30 minutes. In certain embodiments, the dry air or inert gas remains in the drying chamber for at least 30 seconds, at least 1 minute, at least 5 minutes, at least 10 minutes, at least 15 minutes, at least 20 minutes, at least 25 minutes, at least 30 minutes, or at least 1 hour.

In certain embodiments, the vacuum drying and gas filling steps for pre-drying the separator can be repeated at least 2 times, at least 3 times, at least 4 times, at least 5 times, at least 6 times, at least 7 times. , at least 8 times, at least 9 times, at least 10 times, at least 12 times, at least 14 times, at least 16 times, at least 18 times, at least 20 times, at least 22 times, at least 24 times , at least 26 times, at least 28 times, or at least 30 times. In some embodiments, the vacuum drying and gas filling steps may be repeated 2-50 times, 2-40 times, 2-30 times, 2-20 times, 2-10 times, 5-30 times. times, between 5 and 20 times or between 5 and 10 times. In certain embodiments, the vacuum drying and gas filling steps may be repeated 2 or more times.

In some embodiments, the total predry time of vacuum drying and gas filling is from about 15 minutes to about 10 hours, from about 15 minutes to about 8 hours, from about 15 minutes to about 6 hours, from about 15 minutes to about 5 hours, from about 15 minutes to about 4 hours, from about 15 minutes to about 3 hours, from about 15 minutes to about 2 hours, from about 30 minutes to about 4 hours, from about 30 minutes to about 2 hours, from about 1 hour to about 4 hours, or from about 2 hours to about 4 hours. In certain embodiments, the total predry time of vacuum drying and gas filling is at least 15 minutes, at least 30 minutes, at least 1 hour, at least 1.5 hours, at least 2 hours, at least 3 hours. , at least 4 hours or at least 5 hours. In some embodiments, the total vacuum dry and gas fill predry time is less than 10 hours, less than 8 hours, less than 6 hours, less than 5 hours, less than 4 hours, less than 3 hours, less less than 2 hours, less than 1.5 hours, less than 1 hour or less than 30 minutes. After pre-drying, the separator can then be naturally cooled to 50°C or lower before being removed from the drying chamber. In some embodiments, the separator is cooled to 45°C or below, 40°C or below, 35°C or below, 30°C or below, or 25°C or below before being removed from the drying chamber. In certain embodiments, the separator is cooled to room temperature. In some embodiments, the separator is cooled by blowing a dry gas or inert gas in order to reach the target temperature more quickly.

It is not necessary to dry the separator until a very low water content is reached. The remaining water content of the pre-dried separator can be further reduced by the subsequent drying step. In some embodiments, the water content of the pre-dried separator is less than 80 ppm, less than 70 ppm, less than 60 ppm, less than 50 ppm, less than 40 ppm, or less than 30 ppm by weight, based on the total weight of the pre-dried separator.

The pre-dried separator does not need to be used immediately once it dries and can be stored in an environment where the air has a dew point of -10°C to 30°C overnight before being used to prepare the electrode assemblies. However, direct post processing without storage is more energy efficient.

In other embodiments, the coated or uncoated separator can be dried by a freeze dryer. The separator can be frozen first and then the water is removed as vapor from the frozen state. In some embodiments, the separator is first frozen at a freezing temperature between -0°C and -80°C for a period of 1 hour to 5 hours. The freeze-drying apparatus may include a vacuum chamber, a cold trap, a vacuum pump, and a cooling device.

The time of the lyophilization process is variable, but normally the lyophilization can be carried out for a period of about 1 hour to about 20 hours. In certain embodiments, the period of time for lyophilization is from about 1 minute to about 5 hours, from about 1 hour to about 3 hours, from about 1 hour to about 2 hours, from about 2 hours to about 5 hours, from about 2 hours to about 4 hours, or from about 2 hours to about 3 hours.

In some embodiments, the lyophilization process can be carried out under high vacuum. The pressure ranges can be adequately achieved by a publicly known vacuum pump. In certain embodiments, the lyophilization process can also be carried out at near atmospheric pressure. The partial pressure of the water in the drying chamber is kept at a very low value since it is essential to produce a large difference between the vapor pressure of the air in the drying chamber and that of the surface of the separator to ensure sublimation. Lyophilization at or near atmospheric pressure has the advantage of considerably reducing operating costs since the application of high vacuum is not necessary.

In some embodiments, the water content in the pre-dried separator is less than 150 ppm, less than 100 ppm, less than 80 ppm, less than 70 ppm, less than 60 ppm, or less than 50 ppm by weight, based on total weight. of the pre-dried separator.

When the water content of the separator after freeze-drying is more than 150 ppm, the pre-dried separator can be further dried by blowing hot air. In some embodiments, the drying chamber blows hot air into the separator from above and/or below. In certain embodiments, hot air drying is performed at an air velocity of from about 1 meter/second to about 50 meters/second, from about 1 meter/second to about 40 meters/second, from about 1 meter/second to about 30 meters/second or from about 1 meter/second to about 20 meters/second. In other embodiments, a heated inert gas (ie, helium, argon) is used instead of hot air.

The drying gas can be preheated through heat exchange surfaces. In some embodiments, the hot air temperature ranges from about 50°C to about 100°C, from about 60°C to about 100°C, from about 70°C to about 100°C, from about 50°C C to about 90 °C or from about 60 °C to about 90 °C. In certain embodiments, the time period for hot air drying is from about 15 minutes to about 5 hours or from about 1 hour to about 3 hours.

The binder material in the protective porous layer plays the role of binding the inorganic filler on the porous base material. The inorganic filler could also be bound together by the binder material. In certain embodiments, the binder material is an organic polymer. The use of the organic polymer makes it possible to produce a spacer with adequate mechanical flexibility.

In some embodiments, the binder material is selected from the group consisting of an organic-based binder material, a water-based binder material, or a mixture of water-based and organic-based binder materials. In certain embodiments, the binder material is selected from the group consisting of styrene-butadiene rubber (SBR), acrylated styrene-butadiene rubber, acrylonitrile copolymer, acrylonitrile-butadiene rubber, nitrile-butadiene rubber, acrylonitrile-styrene-butadiene copolymer. butadiene, acrylic rubber, butyl rubber, fluorine rubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene/propylene copolymers, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, latex, acrylic resins, phenolic resins, epoxy resins, carboxymethylcellulose (CMC), hydroxypropylcellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylcellulose, cyanoethylsucrose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, pol acid iacrylic acid (PAA), polyacrylate, polymethacrylic acid, polymethacrylate, polyacrylamide, polyurethane, fluoropolymer, chlorinated polymer, a salt of alginic acid, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropene, and combinations thereof. In some embodiments, the alginic acid salt comprises a cation selected from Na, Li, K, Ca, NH4, Mg, Al, or a combination thereof.

In certain embodiments, the binder material is selected from the group consisting of styrene-butadiene rubber, carboxymethylcellulose, polyvinylidene fluoride, acrylonitrile copolymer, polyacrylic acid, polyacrylonitrile, polyvinylidene fluoride-hexafluoropropene, latex, an alginic acid salt, and combinations of them.

In some embodiments, the binder material is SBR, CMC, PAA, a salt of alginic acid, or a combination thereof. In some embodiments, the binder material is an acrylonitrile copolymer. In certain embodiments, the binder material is polyacrylonitrile. In some embodiments, the binder material does not contain styrene-butadiene rubber, carboxymethylcellulose, polyvinylidene fluoride, acrylonitrile copolymer, polyacrylic acid, polyacrylonitrile, polyvinylidene fluoride-hexafluoropropene, latex, or an alginic acid salt.

There is no particular limitation on the mixing ratio between an inorganic filler and a binder material in the protective porous layer of the present invention. The mixing ratio between the inorganic filler and the binder material can be controlled according to the thickness and structure of the protective porous layer to be formed.

In some embodiments, the weight ratio of inorganic filler to binder material in the protective porous layer formed on the porous base material in accordance with the present invention is from about 1:1 to about 99:1, from about 70:30 at about 95:5, about 95:5 to about 35:65, about 65:35 to about 45:55, about 20:80 to about 99:1, about 10:90 to about 99:1, from about 5:95 to about 99:1, from about 3:97 to about 99:1, from about 1:99 to about 99:1, or from about 1:99 to about 1:1.

If the weight ratio of inorganic filler to binder material is less than 1:99, the binder content is so large that the pore size and porosity of the protective porous layer may decrease. When the content of the inorganic filler is greater than 99% by weight, the polymer content is too low to provide sufficient adhesion between the inorganic filler, resulting in degradation of mechanical properties and lower peel strength of a polymer. finally formed protective porous layer.

In certain embodiments, the amount of binder material in the protective porous layer is at least 1%, at least 2%, at least 3%, at least 4%, at least 5%, at least 10% , at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45% or at least 50% by weight , based on the total weight of the protective porous layer. In some embodiments, the amount of binder material in the protective porous layer is at most 1%, at most 2%, at most 3%, at most 4%, at most 5%, at most 10%. , not more than 15%, not more than 20%, not more than 25%, not more than 30%, not more than 35%, not more than 40%, not more than 45% or not more than 50% by weight , based on the total weight of the protective porous layer.

In some embodiments, the amount of the binder material in the protective porous layer is from about 2 wt% to about 10 wt%, from about 3 wt% to about 6 wt%, from about 5 wt% to about 10 wt%. % by weight, from about 7.5% by weight to about 15% by weight, from about 10% by weight to about 20% by weight, from about 15% by weight to about 25% by weight, from about 20% by weight weight to about 40% by weight, or from about 35% by weight to about 50% by weight, based on the total weight of the protective porous layer.

In certain embodiments, the active electrode material of the battery is a cathode material selected from the group consisting of LiCoO2 (LCO), LiNiO2 (LNO), LiNixMnyO2, Lh+zNixMnyCo1-x-yO2, LiNixCoyAlzO2, LiV2O5, LiTiS2, LiMoS2, LiMnO2 , LiCrO2, LiMn2O4 (LMO), LiFeO2, LiFePO4 (LFP), and combinations thereof, wherein each x is independently from 0.3 to 0.8; each y is independently from 0.1 to 0.45; and each z is independently from 0 to 0.2. In certain embodiments, the cathode material is selected from the group consisting of LiCoO2, LiNiO2, LiNixMnyO2, Lh+zNixMnyCo-i-x-yO2, LiNixCoyAlzO2, LiV2O5, LiTiS2, LiMoS2, LiMnO2, LiCrO2, LiMn2O4, LiFeO2, LiFePO4, and combinations of the same, wherein each x is independently from 0.4 to 0.6; each y is independently from 0.2 to 0.4; and each z is independently from 0 to 0.1. In other embodiments, the cathode material is not LiCoO2, LiNiO2, LW2O5, LiTiS2, LiMoS2, LiMnO2, LiCrO2, LiMn2O4, LiFeO2, or LiFePO4. In further embodiments, the cathode material is not LiNixMnyO2, Lh+zNixMnyCo-i-x-yO2, or LiNixCoyAlzO2, where each x is independently from 0.3 to 0.8; each y is independently from 0.1 to 0.45; and each z is independently from 0 to 0.2.

In certain embodiments, the cathodic active material is a nickel-containing cathodic active material. In some embodiments, the nickel-containing cathodic active material is selected from the group consisting of Lh+xNiO2, Lh+xNiaMnbO2, Lh+xNiaCocO2, Lh+xNiaMnbCocO2, Lh+xNiaCocAl(1-a-c)O2, and combinations thereof; where 0<x<0.2, 0<a<1, 0<b<1, 0<c<1, and a+b+c<1. In certain embodiments, the nickel-containing cathodic active material is Lh+xNiaMnbCocO2, where 0<x<0.2, 0.3<a<0.8, 0.1<b<0.3, and 0.1< c<0.3. In certain embodiments, the nickel-containing cathode active material is selected from the group consisting of LiNi0.33Mn0.33Co0.33O2 (NMC333), LiNi0.4Mn0.4Co0.2O2 (NMC442), LiNi0.5Mn0.3Co0.2O2 (NMC532) , LiNi0.6Mn0.2Co0.2O2 (NMC622), LiNi0.7Mn0.15Co0.15O2, LiNi0.8Mn0.1Coci,1O2 (NMC811), LiNi0.8Mn0.05Coci,15O2, Li0.9Mn0.05Co0.05O2, LiNi0.92Mn0 .04Co0.04O2, LiNi0.8Co0.15Al0.05O2 (NCA) LiNi0.5MnO0.5O2, LiNi0.6Mn0.4O2, LiNi0.7Mn0.3O2, LiNi0.8Mn0.2O2, LiNi0.5Co0.5O2, LiNi0.6Co0.4O2 LiNi0.7Co0.3O2 LiNi0.8Co0.2O2 LiNiO2, and combinations thereof. The nickel-containing compound oxide is relatively unstable in a moisture-containing environment. Therefore, the performance of the cathode comprising the nickel-rich cathodic active material is strongly affected by the residual moisture content in a battery.

In some embodiments, the active battery electrode material is an anode material selected from the group consisting of natural graphite particulate material, synthetic graphite particulate material, Sn (tin) particulate material, Li4Ti5O12 particulate material, Si particulate material. (silicon), Si-C composite particulate material and combinations thereof. In other embodiments, the anode material is not a natural graphite particulate material, synthetic graphite particulate material, Sn(tin) particulate material, Li4Ti5O12 particulate material, Si(silicon) particulate material, or Si-(silicon) composite particulate material. c.

In certain embodiments, the amount of each of the cathodic and anodic materials is independently at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90% or at least 95% by weight, based on the total weight of the cathode or anode electrode layer. In some embodiments, the amount of each of the cathode and anode materials is independently at most 50%, at most 55%, at most 60%, at most 65%, at most 70%, at most 75%, at most 80%, at most 85%, at most 90% or at most 95% by weight, based on the total weight of the cathode or anode electrode layer.

In some embodiments, the conductive agent is selected from the group consisting of carbon, carbon black, graphite, expandable graphite, graphene, graphene nanoplatelets, carbon fibers, carbon nanofibers, graphitized carbon flakes, carbon tubes, nanotubes. carbon, activated carbon, mesoporous carbon and combinations thereof. In certain embodiments, the conductive agent is not carbon, carbon black, graphite, expandable graphite, graphene, graphene nanosheets, carbon fibers, carbon nanofibers, graphitized carbon flakes, carbon tubes, carbon nanotubes, activated carbon, or mesoporous carbon.

In certain embodiments, the amount of the conductive agent in each of the cathode and anode electrode layers is independently at least 1%, at least 2%, at least 3%, at least 4%, at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45 % or at least 50% by weight, based on the total weight of the cathode or anode electrode layer. In some embodiments, the amount of the conductive agent in each of the cathode and anode electrode layers is independently at most 1%, at most 2%, at most 3%, at most 4%, at most 5%, maximum 10%, maximum 15%, maximum 20%, maximum 25%, maximum 30%, maximum 35%, maximum 40%, maximum 45% or at most 50% by weight, based on the total weight of the cathode or anode electrode layer.

In some embodiments, the amount of the conductive agent in each of the cathode and anode electrode layers is independently from about 0.05 wt% to about 0.5 wt%, from about 0.1 wt% to about 1% by weight, from about 0.25% by weight to about 2.5% by weight, from about 0.5% by weight to about 5% by weight, from about 2% by weight to about 5% by weight, from about 3% by weight to about 7% by weight or from about 5% by weight to about 10% by weight, based on the total weight of the cathode or anode electrode layer.

An electrode suspension is prepared by dispersing an electrode active material, a binder material, and a conductive agent in a solvent. In some embodiments, the solvent is an aqueous solvent or an organic solvent. In certain embodiments, the aqueous solvent is water. In some embodiments, the organic solvent is N-methyl-2-pyrrolidone (NMP), dimethylformamide, dimethylacetamide, dimethylsulfoxide, or tetrahydrofuran. In some embodiments, the solvent is not N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, dimethylsulfoxide, or tetrahydrofuran. In some embodiments, the solvent is not a mixture of N-methyl-2-pyrrolidone and water.

The electrode suspension is coated onto the current collector to form a coated layer on the current collector. The coated current collector is then dried to prepare an electrode. The electrode suspension is dried at a temperature below 90°C to prevent the suspension from drying out too quickly, which can lead to cracking of the electrode layer. In some embodiments, the coated layer is dried at a temperature of from about 40°C to about 90°C, from about 40°C to about 80°C, from about 40°C to about 70°C, from about 40°C at about 60°C, from about 50°C to about 90°C, from about 50°C to about 80°C, or from about 50°C to about 70°C. In certain embodiments, the coated layer is dried at a temperature of less than about 90°C, less than about 80°C, less than about 70°C, less than about 60°C, or less than about 50°C. In some embodiments, the coated layer is dried at about 40°C, about 50°C, about 60°C, about 70°C, about 80°C, or about 90°C.

After mounting the electrode array, the electrode array is placed in a drying chamber. In some embodiments, the drying chamber is connected to a vacuum pump. In certain embodiments, the drying chamber is connected to a central vacuum supply. A vacuum pump or central vacuum supply is connected to the drying chamber by a suction line equipped with a gas outlet valve. In certain embodiments, the drying chamber is also connected to a gas reservoir containing dry air or inert gas by a tube equipped with a gas inlet valve. When the gas outlet valve is closed and the gas inlet valve is open, the vacuum is lost in the drying chamber. The valve can be a solenoid or needle type or a mass flow controller. Any device that allows proper flow adjustment can be used.

In some embodiments, the electrode array is sparsely stacked. In the loosely stacked electrode array, there is an empty space between the electrode layer and the separator layer, allowing moisture to escape. Therefore, the sparsely stacked electrode array can be effectively dried in a short period of time. On the other hand, when the electrode array was compressed under pressure before drying, the closely packed electrode array has little or no void space between the electrode layer and the separator layer, thereby reducing airflow and drying efficiency.

In certain embodiments, the positive electrode, spacer, and negative electrode are stacked and spirally wound into a roll-like configuration before drying. Since the coil-type electrode assembly is tightly packed, there is also little or no void space between the electrode layer and the separator layer, thereby reducing airflow and drying efficiency. In some embodiments, the electrode assembly is not spirally wound.

To reduce the power required for the pumps, a condenser can be provided between the drying chamber and the pump when drying the electrode array. The condenser condenses the water vapor, which is then separated.

Low temperature drying cannot effectively remove water from the electrode array. However, the layer of the electrode will become brittle and crack easily when subjected to high drying temperatures. In some embodiments, the electrode assembly may be vacuum dried at a temperature of from about 70°C to about 150°C, from about 80°C to about 150°C, from about 90°C to about 150°C, from about 90°C to about 150°C. about 100°C to about 150°C, about 110°C to about 150°C, or about 80°C to about 130°C. In some embodiments, the electrode array may be vacuum dried at a temperature of about 80°C or higher, about 90°C or higher, about 100°C or higher, about 110°C or higher, about 120°C or higher or about 130 °C or higher. In certain embodiments, the electrode assembly may be vacuum dried at a temperature of less than 150°C, less than 145°C, less than 140°C, less than 135°C, less than 130°C, less than 120°C , less than 110 °C, less than 100 °C or less than 90 °C.

In certain embodiments, the period of time to dry the electrode assembly under vacuum is from about 5 minutes to about 12 hours, from about 5 minutes to about 4 hours, from about 5 minutes to about 2 hours, from about 5 minutes to about 1 hour, from about 5 minutes to about 30 minutes, from about 5 minutes to about 15 minutes, from about 15 minutes to about 1 hour, from about 15 minutes to about 3 hours, from about 1 hour to about 10 hours, from about 1 hour to about 8 hours, from about 1 hour to about 6 hours, from about 1 hour to about 4 hours, from about 1 hour to about 2 hours, from about 2 hours to about 12 hours, from about 2 hours to about 8 hours hours, from about 2 hours to about 5 hours, from about From 2 hours to about 3 hours or from about 4 hours to about 12 hours. In some embodiments, the period of time to dry the electrode assembly under vacuum is from about 5 minutes to about 2 hours or from about 15 minutes to about 30 minutes. In certain embodiments, the period of time to dry the electrode assembly under vacuum is at least 15 minutes, at least 30 minutes, at least 1 hour, at least 1.5 hours, at least 2 hours, at least 3 hours, at least 4 hours or at least 5 hours. In some embodiments, the period of time to dry the electrode assembly under vacuum is less than 5 hours, less than 4 hours, less than 3 hours, less than 2 hours, less than 1.5 hours, less than 1 hour, or less. to 30 minutes.

In some embodiments, the electrode array is dried at atmospheric pressure. In certain embodiments, the drying is performed in a vacuum state. In some embodiments, the vacuum state is maintained at a pressure within the range of from about 1x10-4 Pa to about 5x104 Pa, from about 1x10-4 Pa to about 2.5x104 Pa, from about 1x10-4 Pa to about 1x104 Pa, from about 1x10-4Pa to about 5x103 Pa, from about 1x10-4Pa to about 3x103 Pa, from about 1x10-4Pa to about 2x103 Pa, from about 1x10-4Pa to about 1x103 Pa, from about 1x103 Pa to about 5x104 Pa, from from about 1x103 Pa to about 1x104 Pa, from about 1x103 Pa to about 5x103 Pa, from about 1x103 Pa to about 3x103 Pa, or from about 1x103 Pa to about 2x103 Pa. In certain embodiments, the vacuum state is maintained at a pressure less than about 5x104 Pa, less than about 2.5x104 Pa, less than about 1x104 Pa, less than about 5x103 Pa, less less than about 3x103 Pa, less than about 2x103 Pa, or less than about 1x103 Pa. In some embodiments, the vacuum state is maintained at about 5x104 Pa, about 2.5x104 Pa, about 1x104 Pa, about 5x103 Pa, about 3x103 Pa , about 2x103 Pa or about 1x103 Pa.

After a predetermined period of drying time, the drying chamber is vented directly to a gas reservoir containing dry air or inert gas through a gas intake valve. Gas filling can improve the water vapor removal of the drying chamber, thus increasing the water removal efficiency of the electrode array and shortening the drying cycle. In certain embodiments, the inert gas is selected from the group consisting of helium, argon, neon, krypton, xenon, nitrogen, carbon dioxide, and combinations thereof.

In some embodiments, the electrode array may be further dried under vacuum after incubating the electrode array with the dry gas for a predetermined time. This procedure can be repeated as many times as necessary to reduce the moisture content of the electrode array to an appropriate level. In certain methods that are not part of the claimed invention, this procedure can be repeated between 2 and 50 times until the moisture content in the electrode assembly is less than 40 ppm, less than 30 ppm, less than 20 ppm, less than 19 ppm, less than 18 ppm, less than 17 ppm, less than 16 ppm, less than 15 ppm, less than 14 ppm, less than 13 ppm, less than 12 ppm, less than 11 ppm, less than 10 ppm, less than 9 ppm, less than 8 ppm, less than 7 ppm, less than 6 ppm, or less than 5 ppm by weight, based on the total weight of the dry electrode assembly.

In some embodiments, the vacuum drying and gas filling steps may be repeated at least 5 times, at least 6 times, at least 7 times, at least 8 times, at least 9 times, at least 10 times, at least 12 times. , at least 14 times, at least 16 times, at least 18 times, at least 20 times, at least 22 times, at least 24 times, at least 26 times, at least 28 times or at least 30 times. In certain embodiments, the vacuum drying and gas filling steps may be repeated less than 30 times, less than 28 times, less than 26 times, less than 24 times, less than 22 times, less than 20 times, less than 18 times, less than 16 times, less than 14 times, less than 12 times, less than 10 times, less than 8 times, or less than 6 times. In some embodiments, the vacuum drying and gas filling steps may be repeated 5-30 times, 5-20 times, or 5-10 times.

In some embodiments, the total electrode assembly drying processing time is from about 10 hours to about 40 hours, from about 10 hours to about 35 hours, from about 10 hours to about 30 hours, from about 10 hours to about 25 hours. hours, from about 10 hours to about 20 hours, from about 10 hours to about 15 hours, from about 15 hours to about 30 hours, from about 15 hours to about 25 hours, from about 15 hours to about 20 hours, or from about 20 hours hours to about 30 hours. In some embodiments, the total electrode assembly drying processing time is less than about 40 hours, less than about 35 hours, less than about 30 hours, less than about 25 hours, less than about 20 hours, or less than about 15 hours. hours. In certain embodiments, the total electrode assembly drying processing time is at least about 15 hours, at least about 20 hours, at least about 25 hours, at least about 30 hours, or at least about 35 hours.

In some embodiments, the total separator pre-drying and electrode assembly drying processing time is from about 10 hours to about 50 hours, from about 10 hours to about 40 hours, from about 10 hours to about 30 hours, from about 15 hours to about 50 hours, from about 15 hours to about 40 hours, from about 15 hours to about 30 hours, from about 20 hours to about 50 hours, or from about 20 hours to about 40 hours. In certain embodiments, the total separator pre-drying and electrode assembly drying processing time is at least 10 hours, at least 15 hours, at least 20 hours, at least 25 hours, at least 30 hours, at least 35 hours. or at least 40 hours. In some embodiments, the total separator pre-drying and electrode assembly drying processing time is less than 50 hours, less than 40 hours, less than 35 hours, less than 30 hours, less than 25 hours, less than 20 hours or less than 15 hours.

The advantages of the present invention is that most of the manufacturing can take place outside of a dry room. In some embodiments, the assembly process may take place outside of a dry room or glove box. In the present invention, only the step for filling the electrolyte or both the steps for drying the electrode assembly and filling the electrolyte are performed in a dry room or in a glove box. Thus, humidity control in the factory can be avoided, significantly reducing the investment cost.

The presence of moisture is detrimental to battery operation. In general, the water content in the electrode assembly prepared by conventional methods contains an amount of water greater than 100 ppm by weight, based on the total weight of the electrode assembly. Even if the initial battery performance is acceptable, the rate of battery performance deterioration may be unacceptable. In order to be able to achieve a sufficiently high performance of the battery, it would therefore be advantageous to have a low water content in the battery.

In some embodiments, the water content in the dry electrode assembly is from about 5 ppm to about 50 ppm, from about 5 ppm to about 40 ppm, from about 5 ppm to about 30 ppm, from about 5 ppm to about 20 ppm. , from about 5 ppm to about 15 ppm, from about 5 ppm to about 10 ppm, from about 3 ppm to about 30 ppm, from about 3 ppm to about 20 ppm, from about 3 ppm to about 15 ppm, or from about 3 ppm to about 10 ppm by weight, based on the total weight of the dry electrode assembly.

In certain embodiments, the water content in the dry electrode assembly is less than 50 ppm, less than 40 ppm, less than 30 ppm, less than 20 ppm, less than 19 ppm, less than 18 ppm, less than 17 ppm, less than 16 ppm, less than 15 ppm, less than 14 ppm, less than 13 ppm, less than 12 ppm, less than 11 ppm, less than 10 ppm, less than 9 ppm, less than 8 ppm, less than 7 ppm, less than 6 ppm, less than 5 ppm, less than 4 ppm, less than 3 ppm, less than 2 ppm, or less than 1 ppm by weight, based on the total weight of the dry electrode assembly. In some embodiments, the dry electrode array disclosed herein has a water concentration therein of no greater than about 5 ppm by weight, based on the total weight of the dry electrode array.

In some embodiments, the at least one anode and at least one cathode in the dry electrode assembly have a water content of less than 30 ppm, less than 20 ppm, less than 19 ppm, less than 18 ppm, less than 17 ppm, less than 16 ppm, less than 15 ppm, less than 14 ppm, less than 13 ppm, less than 12 ppm, less than 11 ppm, less than 10 ppm, less than 9 ppm, less than 8 ppm, less than 7 ppm, less than 6 ppm, less than 5 ppm, less than 4 ppm or less than 3 ppm by weight, based on the total weight of at least one dry anode and at least one dry cathode. In certain embodiments, wherein the at least one separator in the dry electrode assembly has a water content of less than 30 ppm, less than 20 ppm, less than 19 ppm, less than 18 ppm, less than 17 ppm, less than 16 ppm, less than 15 ppm, less than 14 ppm, less than 13 ppm, less than 12 ppm, less than 11 ppm, less than 10 ppm, less than 9 ppm, less than 8 ppm, less than 7 ppm, less than 6 ppm, less than 5 ppm, or less than 3 ppm by weight, based on the total weight of the dry separator. The separator in the electrode array disclosed herein comprises a low water content, contributing to the reliable performance of lithium ion batteries.

After drying, the electrode array can then be naturally cooled to 50°C or less before being removed from the drying chamber. In some embodiments, the electrode assembly is cooled to 45°C or lower, 40°C or lower, 35°C or lower, 30°C or lower, or 25°C or lower. In certain embodiments, the electrode array is cooled to room temperature. In some embodiments, the electrode array is cooled by blowing a dry gas or inert gas in order to reach the target temperature more quickly.

In battery manufacturing, it is important to have extremely thin separators so that the energy density of the battery can be increased and the size of the battery can be reduced. Good peel strength is important in battery manufacturing because it prevents separator delamination. Therefore, sufficient mechanical strength and high puncture resistance can be obtained. Battery separator having sufficient puncture resistance and peel strength can withstand the rigors of battery manufacturing, particularly in the manufacture of "roll" type batteries.

In the case that the peel strength of the separator is 0.04N/cm or more, the separator has sufficient peel strength and the coating layer will not be separated during the battery manufacturing.

The drying process of the present invention does not affect the final peel strength of the separator. In some embodiments, each of the peel strengths between the porous base material and the protective porous layer of the spacer and the pre-dried spacer is independently 0.03 N/cm or more, 0.04 N/cm or more, 0, 0.05 N/cm or more, 0.06 N/cm or more, 0.07 N/cm or more, 0.08 N/cm or more, 0.09 N/cm or more, 0.1 N/cm or more, 0.11 N/cm or more, 0.12 N/cm or more, 0.13 N/cm or more, 0.14 N/cm or more, or 0.15 N/cm or more. In certain embodiments, the peel strength between the porous base material and the protective porous layer is between 0.03 N/cm and 0.1 N/cm, between 0.03 N/cm and 0.08 N/cm , between 0.03 N/cm and 0.075 N/cm, between 0.03 N/cm and 0.06 N/cm, between 0.05 N/cm and 0.25 N/cm, between 0.05 N/ cm and 0.15 N/cm, between 0.05 N/cm and 0.12 N/cm, or between 0.05 N/cm and 0.1 N/cm.

In certain embodiments, the peel strength of the pre-dried separator is greater than the peel strength of the separator. In some embodiments, the peel strength of the pre-dried separator is less than the peel strength of the separator. In certain embodiments, the peel strength of the pre-dried separator is equal to the peel strength of the separator. In certain embodiments, the difference in peel strength between the pre-dried spacer and the spacer is from about 0.001 N/cm to about 0.1 N/cm, from about 0.001 N/cm to about 0.05 N/cm, from about 0.001 N/cm to about 0.05 N/cm. about 0.001 N/cm to about 0.04 N/cm, about 0.001 N/cm to about 0.03 N/cm, about 0.001 N/cm to about 0.02 N/cm, about 0.001 N/cm to about 0.01 N/cm, from about 0.01 N/cm to about 0.1 N/cm, from about 0.01 N/cm to about 0.05 N/cm, from about 0.01 N/cm cm to about 0.04 N/cm, from about 0.01 N/cm to about 0.03 N/cm, or from about 0.01 to about 0.02 N/cm. In some embodiments, the difference in peel strength between the pre-dried spacer and the spacer is less than 0.1 N/cm, less than 0.05 N/cm, less than 0.04 N/cm, less than 0, 03 N/cm, less than 0.02 N/cm, less than 0.01 N/cm, less than 0.005 N/cm, or less than 0.001 N/cm.

In order to avoid moisture inside the sealed container, the step of filling the electrolyte is carried out in a dry room. After drying, the electrode assembly is placed inside a container, and then an electrolyte is added to fill the pores of all the separator and electrode layers, and each of the gaps between the positive and negative electrodes and the separator in the electrode assembly under an inert atmosphere before sealing.

The method disclosed herein allows for a reduction in the occurrence of defective products and ultimately allows for an improvement in performance, thereby greatly reducing manufacturing costs.

Also provided herein is a lithium battery comprising the electrode assembly prepared by the method disclosed herein.

examples

The water content in the electrode array was measured by Karl-Fisher titration. The electrode array was cut into small 1 cm x 1 cm pieces in a glove box filled with argon gas. The cut electrode array having a size of 1 cm x 1 cm was weighed into a sample vial. The weighed electrode array was then added to a titration vessel for Karl Fischer titration using a Karl Fischer coulometric moisture analyzer (831 KF Coulometer, Metrohm, Switzerland). Measurements were repeated three times to find the average value.

The water content in the separator was measured by Karl-Fisher titration. The electrode array was cut into small 1 cm x 1 cm pieces in a glove box filled with argon gas. The electrode array was separated into anode, cathode and separator layers. The water contents of the separated separator layers were analyzed by Karl Fischer titration. Measurements were repeated three times to find the average value.

The peel strengths of the spacers were measured with a peel tester (obtained from Instron, USA; model no. MTS 5581). The dry electrode array was separated into anode, cathode and separator layers. Each of the separator layers was cut into a rectangular shape having a size of 25 mm x 100 mm. Next, a strip of repair tape (3M; USA; model #810) was affixed to the surface of the spacer having the protective porous coating layer and then compressed with a reciprocating motion of a roller. 2 kg on it to prepare the samples for the peel strength test. Each of the samples was mounted on the peel test equipment, followed by measurement of the peel strength of the repair tape at 180° at room temperature. The repair tape was peeled off at a rate of 50 mm/minute. Measurements were taken at a predetermined range of 10mm to 70mm and repeated 3 times.

Example 1

A) Preparation of the positive electrode

A positive electrode suspension was prepared by mixing 94 wt% cathode material (LNMC TLM 310, obtained from Xinxiang Tianli Energy Co. Ltd., China), 3 wt% carbon black (SuperP; obtained from Timcal Ltd, Bodio , Switzerland) as conductive agent and 0.8% by weight of polyacrylic acid (PAA, no. 181285, obtained from Sigma-Aldrich, USA), 1.5% by weight of styrene butadiene rubber (SBR , AL-2001, obtained from NIPPON A&L INC., Japan) and 0.7% by weight of polyvinylidene fluoride (PVDF; Solef® 5130, obtained from Solvay S.A., Belgium) as binder, which were dispersed in deionized water to form a suspension with a solid content of 50% by weight. The suspension was homogenized with a planetary agitation mixer.

The homogenized suspension was coated on both sides of an aluminum sheet having a thickness of 20 pm using a transfer coating machine (ZY-TSF6-6518, obtained from Jin Fan Zhanyu New Energy Technology Co. Ltd., China) with an areal density of about 26 mg/cm2. The coated films on the aluminum foil were dried for 3 minutes by means of a 24 meter long conveyor hot air drying oven, as a sub-module of the transfer coating machine, operating at a conveyor speed of approximately 8 meters/minute to obtain a positive electrode. The oven with programmed temperature allowed a controllable temperature gradient in which the temperature gradually increased from the inlet temperature of 60 °C to the outlet temperature of 75 °C.

B) Negative electrode preparation

A negative electrode suspension was prepared by mixing 90% by weight of hard carbon (HC; a purity of 99.5%, Ruifute Technology Ltd., Shenzhen, Guangdong, China), 5% by weight of carbon black and 5% by weight of carbon black. weight of polyacrylonitrile in deionized water to form a suspension with a solid content of 50% by weight. The suspension was coated on both sides of a copper foil having a thickness of 9 µm using a transfer coating machine with an areal density of about 15 mg/cm 2 . The coated films on the copper foil were dried at approximately 50°C for 2.4 minutes by a 24 meter long conveyor hot air dryer, operating at a conveyor speed of approximately 10 meters/minute to obtain a negative electrode.

C) Preparation of the separator

An aqueous binder solution was prepared by dissolving 50 g of CMC in 6.55 L of deionized water. To the aqueous binder solution, 100 g of AhO 3 particles (obtained from Taimei Chemicals Co. Ltd., Japan; Product No. TM-100) and 7.5 g of SBR were added. The inorganic particles had an average diameter of 9 pm. After the addition, the suspension was stirred for 30 minutes at room temperature at a stirring speed of 50 rpm to form a suspension.

A 30 cm wide microporous membrane made of polyethylene (Celgard, LLC, USA) with a thickness of 25 pm was then coated with the above suspension by a continuous roll coater having a doctor blade (obtained from Shenzhen KeJINGSTAR Technology Ltd., China; Model No. AFA-EI300-UL). The coated separator was subsequently passed through an oven integrated in the roll coater and dried at a temperature of 100°C in a stream of hot air. The coating speed was in the range of 1.2-1.7 meters/minute. The coating thickness was controlled by an adjustable gap width between a coating blade and a coating surface. A coated spacer having a total thickness of about 30 µm and a porosity of about 62% was obtained. The resulting separator was stored in humid conditions with a dew point of approximately 25 °C for 1 month to simulate the conditions long term storage. The average value of the moisture content of the separator was 500 ppm. After being stored for 1 month, the separator was dried in a vacuum oven at a pressure of 5x103 Pa at 75 °C for 2 hours during the first drying phase. The separator was further dried under vacuum at 5x103 Pa at 90°C for 1.5 hours during the second drying stage. The average value of the moisture content of the separator was 58 ppm.

Separator peel strength

The mean values of the peel strengths of the pre-dried spacer and the raw spacer were 0.08 N/cm and 0.07 N/cm, respectively. Peel strengths were not greatly affected by the drying process.

Example 2

Electrode Assembly Assembly

The resulting cathode and anode films prepared by the methods described in Example 1 were used to prepare the cathode and anode, respectively, by cutting into individual electrode plates. The pre-dried spacer was cut into individual plates. An electrode array was prepared by stacking the anodes, cathodes, and spacers interposed between the positive and negative electrodes in the open air without humidity control. The electrode array was dried in a vacuum oven inside a glove box at a pressure of 5x103 Pa at 100 °C for 2 hours. The drying chamber was then filled with hot dry air having a water content of 5 ppm and a temperature of 90 °C. Hot dry air was held in the drying chamber for 15 minutes before the drying chamber was evacuated. This cycle was repeated 10 times. The average value of the moisture content of the dry electrode assembly was 15 ppm.

Bag-Type Battery Assembly

A bag-type cell was assembled by stacking the dry electrode array in a small box made of a laminated aluminum and plastic film. The cathode and anode electrode plates were kept apart by spacers and the cassette was preformed. An electrolyte was then loaded into the box containing the packed electrodes in an atmosphere of high purity argon with a moisture and oxygen content of < 1 ppm. The electrolyte was a solution of LiPF6 (1M) in a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a 1:1:1 volume ratio. After filling with electrolytes, the bag-type cells were vacuum sealed and then mechanically compressed using a conventional square-shaped punch.

Electrochemical measurements of Example 2

I) Rated capacity

The cell was galvanostatically tested at a current density of C/2 at 25 °C in a battery tester (BTS-5V20A, obtained from Neware Electronics Co. Ltd., China) between 3.0 V and 4.2 V. V. The nominal capacity was approximately 9 Ah.

II) Cyclability performance

The cycling performance of the bag cell was tested by charging and discharging at a constant current rate of 1C between 3.0 V and 4.2 V. The result of the cycling performance test of Example 2 is shown. in figure 1.

Example 3

A) Preparation of the positive electrode

A positive electrode suspension was prepared by mixing 92 wt% cathode material (LiMn2O4, obtained from HuaGuan HengYuan LiTech Co. Ltd., Qingdao, China), 4 wt% carbon black (SuperP; obtained from Timcal Ltd, Bodio , Switzerland) as a conductive agent and 4% by weight of polyvinylidene fluoride (PVDF; Solef® 5130, obtained from Solvay S.A., Belgium) as a binder, which were dispersed in N-methyl-2-pyrrolidone (NMP; purity >99 %, Sigma-Aldrich, USA) to form a suspension with a solid content of 50% by weight. The suspension was homogenized with a planetary agitation mixer.

The homogenized suspension was coated on both sides of an aluminum foil having a thickness of 20 µm using a transfer coating machine with an areal density of about 40 mg/cm 2 . The coated films on the aluminum foil were dried for 6 minutes by a 24 meter long conveyor hot air drying oven as a sub-module of the aluminum foil coating machine. transfer, operating at a conveyor speed of approximately 4 meters/minute to obtain a positive electrode. The oven with programmed temperature allowed a controllable temperature gradient in which the temperature gradually increased from the inlet temperature of 65 °C to the outlet temperature of 80 °C.

B) Negative electrode preparation

A negative electrode suspension was prepared by mixing 90% by weight of hard carbon (HC; 99.5% purity, obtained from Ruifute Technology Ltd., Shenzhen, Guangdong, China) with 1.5% by weight of carboxymethylcellulose (CMC, BSH-12, DKS Co. Ltd., Japan) and 3.5% by weight of SBR (AL-2001, NIPPON A&L INC., Japan) as a binder and 5% by weight of carbon black as a conductive agent, which are dispersed in deionized water to form another suspension with a solid content of 50% by weight. The suspension was coated on both sides of a copper foil having a thickness of 9 pm using a transfer coating machine with an areal density of about 15mg/cm2. The coated films on the copper foil were dried at about 50°C. C for 2.4 minutes by a 24-meter-long conveyor hot-air dryer operating at a conveyor speed of about 10 meters/minute to obtain a negative electrode.

C) Preparation of the separator

An aqueous binder solution was prepared by dissolving 50 g of CMC in 6.55 L of deionized water. To the aqueous binder solution, 100 g of TiO 2 particles (obtained from Shanghai Dian Yang Industry Co. LTD, China) and 7.5 g of SBR were added. The inorganic particles had an average diameter of 10 pm. After the addition, the suspension was stirred for 30 minutes at room temperature at a stirring speed of 50 rpm to form a suspension.

A 30 cm wide PET non-woven fabric (obtained from MITSUBISHI PAPER MILLS LTD, Japan) having a thickness of about 20 µm and a weight per unit area of about 10 g/m 2 was then coated with the above suspension. by a continuous roll coater having a doctor blade (obtained from Shenzhen KEJINGSTAR Technology Ltd., China; model No. AFA-EI300-UL). The coated separator was subsequently passed through an oven integrated in the roll coater and dried at a temperature of 100°C in a stream of hot air. The coating speed was in the range of 1.2-1.7 meters/minute. The coating thickness was controlled by an adjustable gap width between a coating blade and a coating surface. A coated spacer having a total thickness of about 30 µm and a porosity of about 62% was obtained. The separator was stored in humid conditions with a dew point of approximately 20°C for 1 month to simulate long-term storage conditions. The average value of the moisture content of the separator was 1,000 ppm.

After being stored for 1 month, the separator was dried in a vacuum oven at a pressure of 1x103 Pa at 85 °C for 4 hours. The average value of the moisture content of the separator was 43 ppm.

Separator peel strength

The mean values of the peel strengths of the pre-dried spacer and the raw spacer were 0.07 N/cm and 0.06 N/cm, respectively. Peel strengths were not greatly affected by the drying process.

Example 4

Electrode Assembly Assembly

The resulting cathode and anode films prepared by the methods described in Example 3 were used to prepare the cathode and anode, respectively, by cutting into individual electrode plates. The pre-dried spacer was cut into individual plates. An electrode array was prepared by stacking the anodes, cathodes, and spacers interposed between the positive and negative electrodes in the open air without humidity control. The electrode array was dried in a vacuum oven inside a glove box at a pressure of 1x104 Pa at 102°C for 3 hours. The drying chamber was then filled with hot dry air, having a water content of 5 ppm and a temperature of 85°C. Hot, dry nitrogen was held in the drying chamber for 5 minutes before the drying chamber was evacuated. This cycle was repeated 10 times. The average value of the moisture content of the dry electrode assembly was 23 ppm.

Bag-Type Battery Assembly

A bag-type cell was assembled by stacking the dry electrode array in a small box made of a laminated aluminum and plastic film. The cathode and anode electrode plates were kept apart by spacers and the cassette was preformed. An electrolyte was then loaded into the box containing the packed electrodes in an atmosphere of high purity argon with a moisture and oxygen content of < 1 ppm. The electrolyte was a solution of LiPF6 (1 M) in a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) in a volume ratio of 1:1:1. After filling with electrolytes, the bag-type cells were vacuum sealed and then mechanically compressed using a conventional square-shaped punch.

Electrochemical measurements of Example 4

I) Rated capacity

The cell was galvanostatically tested at a current density of C/2 at 25 °C in a battery tester between 3.0 V and 4.2 V. The nominal capacity was approximately 9.1 Ah.

II) Cyclability performance

The cycling performance of the bag-type cell was tested by charging and discharging at a constant current rate of 1C between 3.0 V and 4.2 V. The result of the cycling performance test of Example 4 is shown. in figure 2.

Example 5

A) Preparation of the positive electrode

A positive electrode suspension was prepared by mixing 94% by weight of cathode material LiNi0.33Mn0.33Co0.33O2 (obtained from Shenzhen Tianjiao Technology Co. Ltd., China), 3% by weight of carbon black (SuperP; obtained from Timcal Ltd, Bodio, Switzerland) as conductive agent and 1.5% by weight of polyacrylic acid (PAA, no. 181285, obtained from Sigma-Aldrich, USA) and 1.5% by weight of polyacrylonitrile (LA 132 , Chengdu Indigo Power Sources Co., Ltd., China) as a binder, which were dispersed in deionized water to form a suspension with a solid content of 50% by weight. The suspension was homogenized with a planetary agitation mixer.

The homogenized suspension was coated on both sides of an aluminum foil having a thickness of 20 µm using a transfer coating machine with an areal density of about 32 mg/cm 2 . The coated films on the aluminum foil were dried for 4 minutes by means of a 24 meter long conveyor hot air drying oven, as a sub-module of the transfer coating machine, operating at a conveyor speed of approximately 6 meters/minute to obtain a positive electrode. The oven with programmed temperature allowed a controllable temperature gradient in which the temperature gradually increased from the inlet temperature of 60 °C to the outlet temperature of 75 °C.

B) Negative electrode preparation

A negative electrode slurry was prepared by mixing 90 wt% hard carbon, 5 wt% carbon black and 5 wt% polyacrylonitrile in deionized water to form a 50 wt% solid content slurry. The suspension was coated on both sides of a copper foil having a thickness of 9 µm using a transfer coating machine with an areal density of about 15 mg/cm 2 . The coated films on the copper foil were dried at approximately 50°C for 2.4 minutes by a 24 meter long conveyor hot air dryer, operating at a conveyor speed of approximately 10 meters/minute to obtain a negative electrode.

C) Separator pretreatment

A ceramic-coated PET microporous separator (obtained from MITSUBISHI PAPER MILLS LTD, Japan) having a thickness of about 30 µm was used. The separator was stored in humid conditions with a dew point of approximately 16°C for 1 month to simulate long-term storage conditions. The average value of the moisture content of the separator was 800 ppm.

After being stored for 1 month, the separator was dried in a vacuum oven at a pressure of 2x103 Pa at 90°C for 2.5 hours. The average value of the moisture content of the separator was 52 ppm.

Separator peel strength

The mean values of the peel strengths of the pre-dried spacer and the raw spacer were 0.11 N/cm and 0.09 N/cm, respectively. Peel strengths were not greatly affected by the drying process.

Electrode Assembly Assembly

The resulting cathode and anode films prepared by the methods described in Example 5 were used to prepare the cathode and anode, respectively, by cutting into individual electrode plates. The pre-dried spacer was cut into individual plates. An electrode array was prepared by stacking the anodes, cathodes, and spacers interposed between the positive and negative electrodes in the open air without humidity control. The electrode array was dried in a vacuum oven inside a glove box at a pressure of 1x103 Pa at 110 °C for 2 hours. The drying chamber was then filled with hot dry air, having a water content of 5 ppm and a temperature of 100°C. Hot, dry air was held in the drying chamber for 10 minutes before the drying chamber was evacuated. This cycle was repeated 10 times. The average value of the moisture content of the dry electrode assembly was 18 ppm.

Bag-Type Battery Assembly

A bag-type cell was assembled by stacking the dry electrode array in a small box made of a laminated aluminum and plastic film. The cathode and anode electrode plates were kept apart by spacers and the cassette was preformed. An electrolyte was then loaded into the box containing the packed electrodes in an atmosphere of high purity argon with a moisture and oxygen content of < 1 ppm. The electrolyte was a solution of LiPF6 (1M) in a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a 1:1:1 volume ratio. After filling with electrolytes, the bag-type cells were vacuum sealed and then mechanically compressed using a conventional square-shaped punch.

Electrochemical measurements of Example 6

I) Rated capacity

The cell was galvanostatically tested at a current density of C/2 at 25 °C in a battery tester between 3.0 V and 4.2 V. The nominal capacity was approximately 8.9 Ah.

II) Cyclability performance

The cycling performance of the bag-type cell was tested by charging and discharging at a constant current rate of 1C between 3.0 V and 4.2 V. The result of the cycling performance test of Example 6 is shown. in figure 3.

Example 7

A) Preparation of the positive electrode

A suspension of positive electrodes was prepared by mixing 93% by weight of cathode material LiNi0.33Mn0.33Co0.33O2 (obtained from Shenzhen Tianjiao Technology Co. Ltd., China), 3% by weight of carbon black (SuperP; obtained from Timcal Ltd, Bodio, Switzerland) as a conductive agent and 4% by weight of polyacrylonitrile (LA 132, Chengdu Indigo Power Sources Co., Ltd., China) as a binder, which were dispersed in deionized water to form a suspension with a solid content of the 50% by weight. The suspension was homogenized with a planetary agitation mixer.

The homogenized suspension was coated on both sides of an aluminum foil having a thickness of 20 µm using a transfer coating machine with an areal density of about 40 mg/cm 2 . The coated films on the aluminum foil were dried for 4 minutes by means of a 24 meter long conveyor hot air drying oven, as a sub-module of the transfer coating machine, operating at a conveyor speed of approximately 6 meters/minute to obtain a positive electrode. The oven with programmed temperature allowed a controllable temperature gradient in which the temperature gradually increased from the inlet temperature of 70 °C to the outlet temperature of 93 °C.

B) Negative electrode preparation

A negative electrode slurry was prepared by mixing 90 wt% hard carbon, 5 wt% carbon black and 5 wt% polyacrylonitrile in deionized water to form a 50 wt% solid content slurry. The suspension was coated on both sides of a copper foil having a thickness of 9 µm using a transfer coating machine with an areal density of about 15 mg/cm 2 . The coated films on the copper foil were dried at approximately 50°C for 2.4 minutes by a 24 meter long conveyor hot air dryer, operating at a conveyor speed of approximately 10 meters/minute to obtain a negative electrode.

C) Separator pretreatment

An uncoated microporous spacer made of nonwoven PET fabric (obtained from MITSUBISHI PAPER MILLS LTD, Japan) having a thickness of about 20 µm was used. The separator was stored under conditions humid with a dew point of about 16°C for 1 month to simulate long-term storage conditions. The average value of the moisture content of the separator was 800 ppm.

After being stored for 1 month, the separator was dried in a vacuum oven at a pressure of 2x103 Pa at 100°C for 2 hours. The average value of the moisture content of the separator was 42 ppm. After drying, the water content of the dried separator was significantly reduced.

Electrode Assembly Assembly

The resulting cathode and anode films prepared by the methods described in Example 7 were used to prepare the cathode and anode, respectively, by cutting into individual electrode plates. The pre-dried spacer was cut into individual plates. An electrode array was prepared by stacking the anodes, cathodes, and spacers interposed between the positive and negative electrodes in the open air without humidity control. The electrode array was dried in a vacuum oven inside a glove box at a pressure of 2,000 Pa at 105 °C for 1.5 hours. The drying chamber was then filled with hot dry air, having a water content of 5 ppm and a temperature of 90°C. Hot, dry air was held in the drying chamber for 10 minutes before the drying chamber was evacuated. This cycle was repeated 8 times. The average value of the moisture content of the dry electrode assembly was 18 ppm.

Bag-Type Battery Assembly

A bag cell was assembled according to the method described in Example 2.

Electrochemical measurements of Example 7

I) Rated capacity

The cell was galvanostatically tested at a current density of C/2 at 25 °C in a battery tester between 3.0 V and 4.2 V. The nominal capacity was approximately 10.2 Ah.

II) Cyclability performance

The cycling performance of the bag cell was tested by charging and discharging at a constant current rate of 1C between 3.0 V and 4.2 V.

Example 8* - not according to the present invention

A) Preparation of the positive electrode

A positive electrode suspension was prepared by mixing 93 wt% LiNi0.33Mn0.33O2 cathode material (obtained from Shenzhen Tianjiao Technology Co. Ltd., China), 3 wt% carbon black (SuperP; obtained from Timcal Ltd, Bodium, Switzerland) as a conductive agent and 4% by weight of polyacrylonitrile (LA 132, Chengdu Indigo Power Sources Co., Ltd., China) as a binder, which were dispersed in deionized water to form a suspension with a solid content of 50%. in weigh. The suspension was homogenized with a planetary agitation mixer. The homogenized suspension was coated on both sides of an aluminum foil having a thickness of 20 µm using a transfer coating machine with an areal density of about 39 mg/cm 2 . The coated films on the aluminum foil were dried for 4 minutes by means of a 24 meter long conveyor hot air drying oven, as a sub-module of the transfer coating machine, operating at a conveyor speed of approximately 6 meters/minute to obtain a positive electrode. The oven with programmed temperature allowed a controllable temperature gradient in which the temperature gradually increased from the inlet temperature of 70 °C to the outlet temperature of 90 °C. B) Negative electrode preparation

A negative electrode slurry was prepared by mixing 90 wt% hard carbon, 5 wt% carbon black and 5 wt% polyacrylonitrile in deionized water to form a 50 wt% solid content slurry. The suspension was coated on both sides of a copper foil having a thickness of 9 µm using a transfer coating machine with an areal density of about 15 mg/cm 2 . The coated films on the copper foil were dried at approximately 50°C for 2.4 minutes by a 24 meter long conveyor hot air dryer, operating at a conveyor speed of approximately 10 meters/minute to obtain a negative electrode.

C) Preparation of the separator

The coated spacer was prepared by the method described in Example 3. The spacer was stored at then in humid conditions with a dew point of about 20°C for 1 month to simulate long-term storage conditions. The average value of the moisture content of the separator was 1,000 ppm.

After being stored for 1 month, the separator was dried in a vacuum oven at a pressure of 4.5x103 Pa at 155 °C for 2 hours. The average value of the moisture content of the separator was 11 ppm.

Separator peel strength

The mean values of the peel strengths of the pre-dried spacer and the raw spacer were 0.035 N/cm and 0.075 N/cm, respectively. The peel strength of the separator has decreased significantly after the pre-drying stage. This makes the separator prone to mechanical failure when an electrode assembly is assembled by a high-speed automatic stacking machine. In this case, the spacer suffered degradation during the high temperature heat treatment, in which the aqueous binder material in the coating became brittle. Therefore, a lower temperature is beneficial for slow drying to prevent cracking or embrittlement of the protective porous layer.

Electrode Assembly Assembly

The resulting cathode and anode films prepared by the methods described in Example 8 were used to prepare the cathode and anode, respectively, by cutting into individual electrode plates. The pre-dried spacer was cut into individual plates. An electrode array was prepared by stacking the anodes, cathodes, and spacers interposed between the positive and negative electrodes in the open air without humidity control. The electrode array was dried in a vacuum oven inside a glove box at a pressure of 2,000 Pa at 105 °C for 1.5 hours. The drying chamber was then filled with hot dry air, having a water content of 5 ppm and a temperature of 90°C. Hot, dry air was held in the drying chamber for 10 minutes before the drying chamber was evacuated. This cycle was repeated 8 times. The average value of the moisture content of the dry electrode assembly was 14 ppm.

Bag-Type Battery Assembly

A bag cell was assembled according to the method described in Example 2.

Electrochemical measurements of Example 8

I) Rated capacity

The cell was galvanostatically tested at a current density of C/2 at 25 °C in a battery tester between 3.0 V and 4.2 V. The nominal capacity was approximately 10.2 Ah.

II) Cyclability performance

The cycling performance of the bag cell was tested by charging and discharging at a constant current rate of 1C between 3.0 V and 4.2 V.

Example 9

A) Preparation of the positive electrode

A positive electrode suspension was prepared by mixing 93 wt% LiNi0.5Mn0.3Co0.2O2 cathode material (obtained from Hunan Rui Xiang New Material Co. Ltd., Changsha, China), 3.5 wt% carbon black (SuperP; obtained from Timcal Ltd, Bodio, Switzerland) as a conductive agent and 1.5% by weight of polyacrylic acid (PAA, no. 181285, obtained from Sigma-Aldrich, USA) and 2% by weight of polyacrylonitrile (LA 132, Chengdu Indigo Power Sources Co., Ltd., China) as a binder, which were dispersed in deionized water to form a suspension with a solid content of 50% by weight. The suspension was homogenized with a planetary agitation mixer.

The homogenized suspension was coated on both sides of an aluminum foil having a thickness of 20 µm using a transfer coating machine with an areal density of about 40 mg/cm 2 . The coated films on the aluminum foil were dried for 4 minutes by means of a 24 meter long conveyor hot air drying oven, as a sub-module of the transfer coating machine, operating at a conveyor speed of approximately 6 meters/minute to obtain a positive electrode. The oven with programmed temperature allowed a controllable temperature gradient in which the temperature gradually increased from the inlet temperature of 70 °C to the outlet temperature of 90 °C.

B) Negative electrode preparation

A negative electrode slurry was prepared by mixing 90 wt% hard carbon, 5 wt% carbon black and 5 wt% polyacrylonitrile in deionized water to form a 50 wt% solid content slurry. The suspension was coated on both sides of a copper foil having a thickness of 9 µm using a transfer coating machine with an areal density of about 15 mg/cm2. The coated films on the copper foil were dried to about 50°C for 2.4 minutes by a 24-meter-long conveyor hot-air dryer operating at a conveyor speed of about 10 meters/minute to obtain a negative electrode.

C) Separator pretreatment

A ceramic-coated PI microporous separator (obtained from Jiangxi Advanced Nanofiber Technology Co., Ltd., China) having a thickness of about 20 µm was used. The separator was stored in humid conditions with a dew point of approximately 20°C for 1 month to simulate long-term storage conditions. The average value of the moisture content of the separator was 1,000 ppm.

After being stored for 1 month, the separator was dried in a vacuum oven at a pressure of 1,000 Pa at 120 °C for 2 hours. The average value of the moisture content of the separator was 32 ppm.

Separator peel strength

The mean values of the peel strengths of the pre-dried spacer and the raw spacer were 0.085 N/cm and 0.08 N/cm, respectively. Peel strengths were not greatly affected by the drying process.

Electrode Assembly Assembly

The resulting cathode and anode films prepared by the methods described in Example 9 were used to prepare the cathode and anode, respectively, by cutting into individual electrode plates. The pre-dried spacer was cut into individual plates. An electrode array was prepared by stacking the anodes, cathodes, and spacers interposed between the positive and negative electrodes in the open air without humidity control. The electrode array was dried in a vacuum oven inside a glove box at a pressure of 2,000 Pa at 105 °C for 1.5 hours. The drying chamber was then filled with hot dry air, having a water content of 5 ppm and a temperature of 90°C. Hot, dry air was held in the drying chamber for 10 minutes before the drying chamber was evacuated. This cycle was repeated 8 times. The average value of the moisture content of the dry electrode assembly was 16 ppm.

Bag-Type Battery Assembly

A bag cell was assembled according to the method described in Example 2.

Electrochemical measurements of Example 9

I) Rated capacity

The cell was galvanostatically tested at a current density of C/2 at 25 °C in a battery tester between 3.0 V and 4.2 V. The nominal capacity was approximately 10.7 Ah.

II) Cyclability performance

The cycling performance of the bag cell was tested by charging and discharging at a constant current rate of 1C between 3.0 V and 4.2 V.

Example 10

Separator pretreatment

A ceramic-coated PET microporous separator (obtained from MITSUBISHI PAPER MILLS LTD, Japan) having a thickness of about 30 µm was used. The separator was stored in humid conditions with a dew point of approximately 20°C for 1 month to simulate long-term storage conditions. The average value of the moisture content of the separator was 1,000 ppm.

After being stored for 1 month, the separator was dried in a vacuum oven at a pressure of 2,000 Pa at 85°C for 1 hour. The drying chamber was then filled with hot dry air, having a water content of 5 ppm and a temperature of 90°C. Hot, dry air was held in the drying chamber for 10 minutes before the drying chamber was evacuated. This cycle was repeated 5 times. The average value of the moisture content of the separator was 13 ppm.

Separator peel strength

The mean values of the peel strengths of the pre-dried spacer and the raw spacer were 0.09 N/cm and 0.085 N/cm, respectively. Peel strengths were not greatly affected by the drying process.

Electrode Assembly Assembly

Positive and negative electrodes were prepared by the method described in Example 5. An electrode array was prepared by the method described in Example 2. The electrode array was dried by the method described in Example 6. The average value of the moisture content of the dry electrode array was 9 ppm.

Bag-Type Battery Assembly

A bag cell was assembled according to the method described in Example 2.

Electrochemical measurements of Example 10

I) Rated capacity

The cell was galvanostatically tested at a current density of C/2 at 25 °C in a battery tester between 3.0 V and 4.2 V. The nominal capacity was approximately 10.0 Ah.

II) Cyclability performance

The cycling performance of the bag cell was tested by charging and discharging at a constant current rate of 1C between 3.0 V and 4.2 V.

Example 11

Separator pretreatment

A ceramic-coated PET microporous separator (obtained from MITSUBISHI PAPER MILLS LTD, Japan) having a thickness of about 30 µm was used. The separator was stored in humid conditions with a dew point of approximately 20°C for 1 month to simulate long-term storage conditions. The average value of the moisture content of the separator was 1,000 ppm.

After being stored for 1 month, the separator was dried in a vacuum oven at a pressure of 1,000 Pa at 110 °C for 3 hours. The average value of the moisture content of the separator was 37 ppm.

Separator peel strength

The mean values of the peel strengths of the pre-dried spacer and the raw spacer were 0.06 N/cm and 0.07 N/cm, respectively. Peel strengths were not greatly affected by the drying process.

Electrode Assembly Assembly

Positive and negative electrodes were prepared by the method described in Example 5. An electrode array was prepared by the method described in Example 2. An electrode array was prepared by stacking the anodes, cathodes, and spacers interposed between the electrode positive and negative outdoors without humidity control. The electrode array was spirally wound in a coil configuration. The electrode array was then dried in a vacuum oven inside a glove box at a pressure of 1,000 Pa at 110 °C for 3 hours. The drying chamber was then filled with hot dry air, having a water content of 5 ppm and a temperature of 90°C. Hot, dry air was held in the drying chamber for 10 minutes before the drying chamber was evacuated. This cycle was repeated 10 times. The average value of the moisture content of the dry electrode assembly was 19 ppm.

Bag-Type Battery Assembly

A bag cell was assembled according to the method described in Example 2.

Electrochemical measurements of Example 11

I) Rated capacity

The cell was galvanostatically tested at a current density of C/2 at 25 °C in a battery tester between 3.0 V and 4.2 V. The nominal capacity was approximately 10.1 Ah.

II) Cyclability performance

The cycling performance of the bag cell was tested by charging and discharging at a constant current rate of 1C between 3.0 V and 4.2 V.

Comparative Example 1

Electrode Assembly Assembly

Positive and negative electrodes were prepared by the method described in Example 5. One set of electrodes was prepared by the method described in Example 2. One set of electrodes was dried by the method described in Example 6 except that the separator was not previously dried. The average value of the moisture content of the dry electrode assembly was 222 ppm.

Bag-Type Battery Assembly

A bag cell was assembled according to the method described in Example 2. Electrochemical Measurements of Comparative Example 1

I) Rated capacity

The cell was galvanostatically tested at a current density of C/2 at 25 °C in a battery tester between 3.0 V and 4.2 V. The nominal capacity was approximately 9.9 Ah.

II) Cyclability performance

The cycling performance of the bag cell was tested by charging and discharging at a constant current rate of 1C between 3.0 V and 4.2 V.

Comparative Example 2

Separator pretreatment

A separator was processed by the method described in Example 5 except that the separator was dried at atmospheric pressure for 12 hours instead of at reduced pressure for 2.5 hours. The average value of the moisture content of the processed separator was 240 ppm.

Separator peel strength

The average values of the peel strengths of the processed separator and the unprocessed separator were 0.085 N/cm and 0.08 N/cm, respectively. Peel strengths were not greatly affected by the drying process.

Electrode Assembly Assembly

Positive and negative electrodes were prepared by the method described in Example 5. One set of electrodes was prepared by the method described in Example 2. One set of electrodes was dried by the method described in Example 6. The average value of the moisture content of the dry electrode array was 145 ppm.

Bag-Type Battery Assembly

A bag cell was assembled according to the method described in Example 2.

Electrochemical Measurements of Comparative Example 2

I) Rated capacity

The cell was galvanostatically tested at a current density of C/2 at 25 °C in a battery tester between 3.0 V and 4.2 V. The nominal capacity was approximately 10.2 Ah.

II) Cyclability performance

The cycling performance of the bag cell was tested by charging and discharging at a constant current rate of 1C between 3.0 V and 4.2 V.

Comparative Example 3

Separator pretreatment

A separator was pre-dried by the method described in Example 5 except that the separator was dried at 50°C instead of 90°C with gas filling. The drying chamber was filled with hot dry air, which had a water content of 5 ppm and a temperature of 40 °C. Hot, dry air was held in the drying chamber for 15 minutes before the drying chamber was evacuated. This cycle was repeated 8 times. The average value of the moisture content of the separator was 117 ppm.

Separator peel strength

The mean values of the peel strengths of the pre-dried spacer and the raw spacer were 0.075 N/cm and 0.06 N/cm, respectively. Peel strengths were not greatly affected by the drying process.

Electrode Assembly Assembly

Positive and negative electrodes were prepared by the method described in Example 5. One set of electrodes was prepared by the method described in Example 2. One set of electrodes was dried by the method described in Example 6. The average value of the moisture content of the dry electrode array was 79 ppm.

Bag-Type Battery Assembly

A bag cell was assembled according to the method described in Example 2.

Electrochemical Measurements of Comparative Example 3

I) Rated capacity

The cell was galvanostatically tested at a current density of C/2 at 25 °C in a battery tester between 3.0 V and 4.2 V. The nominal capacity was approximately 10.1 Ah.

II) Cyclability performance

The cycling performance of the bag cell was tested by charging and discharging at a constant current rate of 1C between 3.0 V and 4.2 V.

Comparative Example 4

Separator pretreatment

A separator was previously dried by the method described in Example 5. The average value of the moisture content of the separator was 48 ppm.

Separator peel strength

The mean values of the peel strengths of the pre-dried spacer and the raw spacer were 0.09 N/cm and 0.07 N/cm, respectively. Peel strengths were not greatly affected by the drying process.

Electrode Assembly Assembly

Positive and negative electrodes were prepared by the method described in Example 5. An electrode array was prepared by the method described in Example 2. The electrode array was dried by the method described in Example 6, except that the electrode array of electrodes was dried at 160 °C instead of 110 °C. The mean value of the moisture content of the dry electrode array was 18 ppm.

Bag-Type Battery Assembly

A bag cell was assembled according to the method described in Example 2.

Electrochemical Measurements of Comparative Example 4

I) Rated capacity

The cell was galvanostatically tested at a current density of C/2 at 25 °C in a battery tester between 3.0 V and 4.2 V. The nominal capacity was approximately 10.2 Ah.

II) Cyclability performance

The cycling performance of the bag cell was tested by charging and discharging at a constant current rate of 1C between 3.0 V and 4.2 V.

Comparative Example 5

Separator pretreatment

A separator was previously dried by the method described in Example 5. The average value of the moisture content of the separator was 50 ppm.

Separator peel strength

The mean values of the peel strengths of the pre-dried spacer and the raw spacer were 0.08 N/cm and 0.06 N/cm, respectively. Peel strengths were not greatly affected by the drying process.

Electrode Assembly Assembly

Positive and negative electrodes were prepared by the method described in Example 5. One set of electrodes was prepared by the method described in Example 2. One set of electrodes was prepared and dried by the method described in Example 6, except that the electrode array was dried at 65°C instead of 110°C. The mean value of the moisture content of the dry electrode array was 101 ppm.

Bag-Type Battery Assembly

A bag cell was assembled according to the method described in Example 2.

Electrochemical Measurements of Comparative Example 5

I) Rated capacity

The cell was galvanostatically tested at a current density of C/2 at 25 °C in a battery tester between 3.0 V and 4.2 V. The nominal capacity was approximately 9.8 Ah.

II) Cyclability performance

The cycling performance of the bag cell was tested by charging and discharging at a constant current rate of 1C between 3.0 V and 4.2 V.

Comparative Example 6

Separator pretreatment

A separator was previously dried by the method described in Example 5. The average value of the moisture content of the separator was 47 ppm.

Separator peel strength

The mean values of the peel strengths of the pre-dried spacer and the raw spacer were 0.075 N/cm and 0.06 N/cm, respectively. Peel strengths were not greatly affected by the drying process.

Electrode Assembly Assembly

Positive and negative electrodes were prepared by the method described in Example 5. A electrode array by the method described in Example 2. The electrode array was dried by the method described in Example 6, except that the electrode array was dried continuously at 110°C for 24 hours without repeating the filling and drying steps. emptied. The average value of the moisture content of the dry electrode assembly was 164 ppm.

Bag-Type Battery Assembly

A bag cell was assembled according to the method described in Example 2.

Electrochemical Measurements of Comparative Example 6

I) Rated capacity

The cell was galvanostatically tested at a current density of C/2 at 25 °C in a battery tester between 3.0 V and 4.2 V. The nominal capacity was approximately 10.1 Ah.

II) Cyclability performance

The cycling performance of the bag cell was tested by charging and discharging at a constant current rate of 1C between 3.0 V and 4.2 V.

Comparative example 7

Separator pretreatment

A separator was previously dried by the method described in Example 5. The average value of the moisture content of the separator was 52 ppm.

Separator peel strength

The mean values of the peel strengths of the pre-dried spacer and the raw spacer were 0.075 N/cm and 0.07 N/cm, respectively. Peel strengths were not greatly affected by the drying process.

Electrode Assembly Assembly

Positive and negative electrodes were prepared by the method described in Example 5. An electrode array was prepared by the method described in Example 2. The electrode array was dried by the method described in Example 6, except that the number of vacuum drying and gas filling cycles was 3 instead of 10. The average value of the moisture content of the dry electrode assembly was 50 ppm.

Bag-Type Battery Assembly

A bag cell was assembled according to the method described in Example 2.

Electrochemical Measurements of Comparative Example 7

I) Rated capacity

The cell was galvanostatically tested at a current density of C/2 at 25 °C in a battery tester between 3.0 V and 4.2 V. The nominal capacity was approximately 10.3 Ah.

II) Cyclability performance

The cycling performance of the bag cell was tested by charging and discharging at a constant current rate of 1C between 3.0 V and 4.2 V.

Comparative example 8

Separator pretreatment

A ceramic-coated PET microporous separator (obtained from MITSUBISHI PAPER MILLS LTD, Japan) having a thickness of about 30 µm was used. The separator was stored in humid conditions with a dew point of approximately 20°C for 1 month to simulate long-term storage conditions. The average value of the moisture content of the separator was 800 ppm.

After being stored for 1 month, the separator was dried in a vacuum oven at a pressure of 1,000 Pa at 155 °C for 2 hours. The average value of the moisture content of the separator was 15 ppm.

Separator peel strength

The mean values of the peel strengths of the pre-dried spacer and the raw spacer were 0.03 N/cm and 0.075 N/cm, respectively. The peel strength of the separator has decreased significantly after the pre-drying stage.

Electrode Assembly Assembly

Positive and negative electrodes were prepared by the method described in Example 5. An electrode array was prepared by the method described in Example 2. An electrode array was prepared by stacking the anodes, cathodes, and spacers interposed between the electrode positive and negative electrode and spirally wound in a roll-type configuration in the open air without humidity control. The electrode array was then dried in a vacuum oven inside a glove box at a pressure of 1,000 Pa at 110 °C for 3 hours. The drying chamber was then filled with hot dry air, having a water content of 5 ppm and a temperature of 100°C. Hot, dry air was held in the drying chamber for 10 minutes before the drying chamber was evacuated. This cycle was repeated 10 times. The average value of the moisture content of the dry electrode array was 20 ppm.

Bag-Type Battery Assembly

A bag cell was assembled according to the method described in Example 2.

Electrochemical Measurements of Comparative Example 8

I) Rated capacity

The cell was galvanostatically tested at a current density of C/2 at 25 °C in a battery tester between 3.0 V and 4.2 V. The nominal capacity was approximately 10.1 Ah.

II) Cyclability performance

The cycling performance of the bag cell was tested by charging and discharging at a constant current rate of 1C between 3.0 V and 4.2 V.

The choice of separator and electrode formulation of each of these Examples and Comparative Examples are summarized in Table 1 below. The separator drying conditions of each of these Examples and Comparative Examples are shown in Table 2 below. The water content and separator peel strength of each of these Examples and Comparative Examples are shown in Table 3. The drying conditions of the electrode assembly of each of these Examples and Comparative Examples are shown in Table 4 next. The water content of the electrode array and the cyclability performance of these Examples and Comparative Examples are shown in Table 5 below. The electrochemical tests of Examples 2-7 and 9-11 show the good electrochemical stability of the battery over a wide range of potentials, as well as excellent cycle performance.

Table 1

No. Cathode material Cathode binder material Solvent Separator

Cathode Anode Base material Coating Example 1 NMC333 PAA+SBR+PVDF H 2 O H 2 O EP Yes Example 3 LMO PVDF NMP H 2 O PET Yes Example 5 NMC333 PAA+LA132 H 2 O H 2 O PET Yes E em lo 7 NMC333 LA132 H 2 O H 2 O PET #

Comparative Example 7 NMC333 PAA+LA132 H 2 O H 2 O PET Yes Comparative Example 81 NMC333 PAA+LA132 H 2 O H 2 O PET Yes Note: 1 The bag cell electrode assembly was spirally wound into a roll-type configuration before drying it.

Table 2

No. Conditions for separator drying Total time Vacuum drying Gas filling (hours)

^Time Temp. of Time No. of

Pressure (Pa) Temp. (°C)

(h) gas (°C) (min) cycle

100

2

/ 2 Ejemplo 8* 4.500 155 2 / / / 2 Ejemplo 9 1.000 120 2 / / / 2 Ejemplo 10 2.000 85 1 90 10 5 5,8 Ejemplo 11 1.000 110 3 / / / 3 EjemploExample 1 5,000 75.90 2, 1.5 / / / 3.5 Example 3 1,000 85 4 / / / 4 Example 5 2,000 90 2.5 / / / 2.5 Example 7 2,000

100

two

/ 2 Example 8* 4,500 155 2 / / / 2 Example 9 1,000 120 2 / / / 2 Example 10 2,000 85 1 90 10 5 5.8 Example 11 1,000 110 3 / / / 3 Example

comparison 1 ^{/ / / / / / /} Example

_{comparative 2} 101.325 90 12 / / / 12 Example

_{Comparative 3} 2,000 50 2.5 40 15 8 22 Example

_{comparative 4} 2,000 90 2.5 / / / 2.5 Example

_{Comparative 5} 2,000 90 2.5 / / / 2.5 Example

_{comparative 6} 2,000 90 2.5 / / / 2.5 Example

_{comparative 7} 2,000 90 2.5 / / / 2.5

Example

_{comparative 8} 1,000 155 2 / / / 2

Table 3

No. _____________________________ Divider

0,075

0,035 Ejemplo 9 >1.000 32 0,08 0,085 Ejemplo 10 >1.000 13 0,085 0,09 Ejemplo 11 >1.000 37 0,07 0,06 Ejemplo comparativo 1 >800 / 0,06 / Ejemplo comparativo 2 >800 240 0,08 0,085 Ejemplo comparativo 3 >800 117 0,06 0,075 Ejemplo comparativo 4 >800 48 0,07 0,09 Ejemplo comparativo 5 >800 50 0,06 0,08 Ejemplo comparativo 6 >800 47 0,06 0,075 Ejemplo comparativo 7 >800 52 0,07 0,075 Ejemplo comparativo 8 >800 15 0,075 0,03Water content (ppm) Peel strength (N/cm) Before After Before After pre-drying pre-drying pre-drying pre-drying Example 1 >500 58 0.07 0.08 Example 3 >1,000 43 0.06 0.07 Example 5 >800 52 0.09 0.11 Example 7 >800 42 / / Example 8* >1,000

0.075

0.035 Example 9 >1,000 32 0.08 0.085 Example 10 >1,000 13 0.085 0.09 Example 11 >1,000 37 0.07 0.06 Comparative Example 1 >800 / 0.06 / Comparative Example 2 >800 240 0.08 0.085 Comparative Example 3 >800 117 0.06 0.075 Comparative Example 4 >800 48 0.07 0.09 Comparative Example 5 >800 50 0.06 0.08 Comparative Example 6 >800 47 0.06 0.075 Comparative Example 7 >800 52 0.07 0.075 Comparative Example 8 >800 15 0.075 0.03

Table 4

No. Conditions for drying the electrode assembly Total time Vacuum drying Gas filling (hours) Pressure Temp Time Temp. of Time No. of

(Pa) (°C) (h) gas (°C) (min) cycle

Example 2 5,000 100 2 90 15 10 22.5 Example 4 10,000 102 3 85 5 10 30.8 Example 6 1,000 110 2 100 10 10 21.7 Example 7 2,000 105 1.5 90 10 8 13.3 (continuation)

No. Conditions for drying the electrode assembly Total time Vacuum drying Gas filling (hours) Pressure Temp Time Temp. of Time No. of

(Pa) (°C) (h) gas (°C) (min) cycle

Example 8* 2,000 105 1.5 90 10 8 13.3 Example 9 2,000 105 1.5 90 10 8 13.3 Example 10 1,000 110 2 100 10 10 21.7 Example 11 1,000 110 3 90 10 10 31.7 Example

_{comparative 1} 1,000 110 2 100 10 10 21.7 Example

_{comparative 2} 1,000 110 2 100 10 10 21.7 Example

_{comparative 3} 1,000 110 2 100 10 10 21.7 Example

_{comparative 4} 1,000 160 2 100 10 10 21.7 Example

_{comparative 5} 1,000 65 2 100 10 10 21.7 Example

_{comparative 6} 1,000 110 24 / / / 24 Example

_{comparative 7} 1,000 110 2 100 10 3 6.5 Example

_{comparative 8} 1,000 110 3 100 10 10 31.7

Table 5

561

94,3

No. Water content of electrode assembly Capacity Retention (ppm) Cycle No. Retention (%) Example 2 15 598 93.9 Example 4 23 452 95.0 Example 6

561

94.3

94,7 Ejemplo comparativo 8 20 250 94,4Example 7 18 512 94.1 Example 8* 14 216 94.7 Example 9 16 607 94.4 Example 10 9 634 94.2 Example 11 19 560 94.3 Comparative Example 1 222 186 94 Comparative Example 2 145 222 94.4 Comparative Example 3 79 292 94.1 Comparative Example 4 18 170 94.2 Comparative Example 5 101 220 94.5 Comparative Example 6 164 230 94.3 Comparative Example 7 50 260

94.7 Comparative example 8 20 250 94.4

* Tables 1-5: Example 8 not according to the present invention |

Claims (15)

1. A method of preparing an electrode assembly, comprising the steps of: 1) pre-drying a separator under vacuum at a pressure of less than 25 kPa and a temperature of 50 °C to 150 °C in a drying chamber to obtain a pre-dried separator; 2) stacking at least one anode, at least one cathode and at least one pre-dried separator interposed between the at least one anode and at least one cathode to obtain the set of electrodes; 3) dry the electrode array under vacuum at a temperature of about 70°C to about 150°C; 4) fill the drying chamber with dry air or inert gas; Y 5) repeat steps 3) and 4) at least 5 times; where each iteration of step 3) lasts for a period of time from 5 minutes to 12 hours; where the water content of the pre-dried separator is less than 80 ppm in weight, based on the total weight of the pre-dried separator, measured by coulometric Karl-Fischer titration. 2. The method of claim 1, wherein the separator is a nonwoven fabric consisting of natural or polymeric fibers, and wherein the polymeric fibers have a melting point of 200°C or higher. 3. The method of claim 1, wherein the spacer is made of polymeric fibers selected from the group consisting of polyolefin, ultra-high molecular weight polyethylene, polypropylene, polypropylene/polyethylene copolymer, polybutylene, polypentene, polyacetal, polyamide, polycarbonate, polyimide, polyether ether ketone, polysulfones, polyphenylene oxide, polyphenylene sulfide, polyacrylonitrile, polyvinylidene fluoride, polyoxymethylene, polyvinylpyrrolidone, polyester, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalene, polybutylene naphthalate, and combinations thereof. 4. The method of claim 1, wherein the separator is pre-dried for a period of time from about 2 hours to about 12 hours, or from about 2 hours to about 8 hours. 5. The method of claim 1, further comprising a step of filling the drying chamber with dry air or inert gas after step 1). 6. The method of claim 5, further comprising repeating the vacuum drying and gas filling steps at least 2 times. 7. The method of claim 1, wherein the separator comprises a porous base material and a protective porous layer coating one or both surfaces of the porous base material, wherein the protective porous layer comprises a binder material and an inorganic filler, and wherein the peel strength between the porous base material and the protective porous layer is 0.04 N/cm or more, or 0.1 N/cm or more. 8. The method of claim 7, wherein the inorganic filler is selected from the group consisting of AhO3, SiO2, TO2, ZrO2, BaOx, ZnO, CaCO3, TiN, AlN, MTO3, K2OnTiO2, Na2OmTiO2, and combinations thereof. , where X is 1 or 2; M is Ba, Sr or Ca; n is 1, 2, 4, 6 or 8; and m is 3 or 6; and wherein the binder material is selected from the group consisting of styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile copolymer, acrylonitrile-butadiene rubber, nitrile-butadiene rubber, acrylonitrile-styrene-butadiene copolymer, Acryl, Butyl Rubber, Fluorine Rubber, Polytetrafluoroethylene, Polyethylene, Polypropylene, Ethylene/Propylene Copolymers, Polybutadiene, Polyethylene Oxide, Chlorosulfonated Polyethylene, Polyvinylpyrrolidone, Polyvinylpyridine, Polyvinyl Alcohol, Polyvinyl Acetate, Polyepichlorohydrin, Polyphosphazene, Polyacrylonitrile, Polystyrene, latex, acrylic resins, phenolic resins, epoxy resins, carboxymethylcellulose, hydroxypropylcellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylcellulose, cyanoethylsucrose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate , acid p olymethacrylic, polymethacrylate, polyacrylamide, polyurethane, fluoropolymer, chlorinated polymer, alginic acid salt, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropene, and combinations thereof. 9. The method of claim 8, wherein the weight ratio of inorganic filler to binder material is from about 99:1 to about 1:1. 10. The method of claim 1, wherein the separator has a porosity of from about 40% to about 97%. 11. The method of claim 1, wherein the electrode assembly is dried at a pressure of less than 25 kPa, less than 15 kPa, less than 10 kPa or less than 5 kPa. 12. The method of claim 1, wherein the electrode assembly is dried for a period of time from about 2 hours to about 24 hours, or from about 4 hours to about 12 hours. 13. The method of claim 1, wherein the water content of the separator is greater than 500 wppm, based on the total weight of the separator. 14. The method of claim 1, wherein the water content of the pre-dried separator is less than 50 ppm by weight, based on the total weight of the pre-dried separator. 15. The method of claim 1, wherein the water content of the dry electrode assembly is less than 20 ppm by weight, based on the total weight of the dry electrode assembly.